With executive compensation being thoroughly vetted — and not just at companies that take federal bailout money — will closer scrutiny of directors’ pay be far behind?

Maybe not, though until recently, few shareholders have objected to board compensation, despite the fact that it has risen steadily in recent years. That comfort came mostly out of a desire to attract and retain directors who are motivated and committed to their oversight roles.

Now one corporate governance research firm is seeing a slight shift in that attitude. “Just in this past year, I’ve started to notice a few people saying, about some companies at least, that the directors are being paid a lot of money, but are they really doing that good of a job?” said Paul Hodgson, senior research associate with The Corporate Library.

Still, Hodgson isn’t sold on the idea that a revolution is at hand, at least not yet. “I’ll believe it when I see it. I don’t think it will be particularly widespread,” he added.

One thing that is sure to show up in this year’s crop of proxy statements is the reduced value of stock and stock options used as compensation for directors. Because of the steep market losses, many proxies filed this year, and probably next year too, will show directors as having had negative compensation.

That has already happened to some companies. At one, Thornburg Mortgage, the negative value of equity-based compensation pushed the company to record the steepest decline noted in board pay in The Corporate Library’s Director Pay 2008 study.

The study, released yesterday, included non-executive director compensation for 3,096 companies. Most of them were in the Russell 3000 index, but there was a smattering of others, some of which had fallen out of the index but are expected to reappear in it, and some the research firm covers because of client requests. The study examined 2008 proxies filed before August 1, so the reported data mostly reflects compensation paid during 2007 fiscal years.

According to the report, it was the third straight year of double-digit increases for both individual directors and entire boards. Individuals earned a median of almost 12 percent more than the previous year, but because the average board shrunk in size, the median total board pay climbed only 11 percent.

Hodgson attributed the steady climb of director compensation to the tightened regulatory environment spurred by the big corporate scandals earlier in the decade and the resulting passage of the Sarbanes-Oxley Act.

The company with the highest board compensation was Valero Energy Corporation, with almost $16.5 million. Then came Freeport McMoRan Copper & Gold ($14.7 million), Alleghany Corporation ($11.1 million), Sun Microsystems ($9.7 million), and Dell Inc. ($9.4 million).

However, the figures for many companies at the high end of the list were distorted by very large compensation awarded to one or two directors who tended to be former CEOs of the companies. By eliminating companies that had up to two directors who received more than 50 percent of total board compensation, a very different list emerged. Freeman McMoRan moved to the top, and the other four companies among the first five were replaced by Gilead Sciences, Goldman Sachs, XL Capital, and American Capital Strategies.

Among individuals, Sun Microsystems chairman and former CEO Scott McNealy was the leader of the pay pack among people who served on a single board, pulling down compensation worth about $9.2 million. That amount included $1 million in cash fees, $2.2 million in stock awards, $3.3 million in option awards, $1.6 million in non-equity incentives, $831,000 in increased value of his pension and non-qualified deferred compensation, and $191,000 in other compensation.

The highest-paid directors who were not former CEOs of the companies for which they served were Dell’s Donald Carty, News Corporation’s Arthur Siskind, and Icahn Enterprises’ Vincent Intrieri, all collecting just under $4 million.

The amount recorded for Carty’s compensation was paid during what Dell calls fiscal 2008, because it ended on January 29 of that year, and before Carty took over as the company’s CFO in early 2007. He resigned the executive position in June 2008 but remained on the board.

As for total compensation earned from all boards served on, Sun’s McNealy still led the list even though he was on just one board. The highest-paid person who served on multiple boards was Michael Marks (SanDisk, Crocs, Schlumberger, and Sun) with $7.1 million and John Huff (J.C. Penney, Oceaneering International, BJ Services, and Suncor Energy) with $6.8 million.

Among financial companies, which currently are under extreme scrutiny regarding pay for executives, Goldman Sachs paid its directors the most, at $6.4 million. Total board compensation was $4.1 million at Wachovia, $3.9 million at American International Group at $3.9 million, and $3.7 million at Morgan Stanley.

The study also showed that there were notable differences in board pay policy among financial firms. “You couldn’t say, ‘This is what you expect to find for director compensation at financial services companies.’ They were all over the map,” said Hodgson.

For example, the lead director was paid $100,000 at Freddie Mac, while the going rate was $25,000 to $30,000 at comparable companies, pointed out Greg Ruel, research associate at The Corporate Library, who co-wrote the report with Hodgson. In another example, directors at Lehman Brothers earned $25,000 for attending committee meetings, compared to only $1,500 for AIG and Washington Mutual directors. There were also vast differences in equity compensation practices within the financial group.

Overall director compensation for financial firms, at least those in the mid-market range, is far less than for other high-profile industries. A recent BDO Seidman study of 250 public companies with less than $950 million in annual revenue found that among financial firms, compensation has not kept up with the perceived increase in risk of being a director. Average per-person board pay at such firms was $59,000, compared to $120,000 for technology companies and $105,000 for energy companies.

The BDO study also reported that the top determinant of board compensation is where a company exists in its business life cycle. It divided its survey base — which looked at the manufacturing and real estate sectors in addition into financial services, technology, and energy — into “growth-phase” companies ($114,000 average), “introducing-phase” companies ($96,000), “decline-phase” companies ($92,000), and “mature-phase” companies ($82,000).

Meanwhile, The Corporate Library study, for the second year in a row, revealed that women board members earned significantly higher median pay than men, $131,000 to $117,000, although average compensation was virtually equal, reflecting the greater prevalence of very large awards for men.

Hodgson said that last year he studied the data painstakingly to determine why women were making more than men and came up with no satisfactory explanation. He turned to The Corporate Library’s clients for help, asking them to offer explanations. No client was entirely convincing, he said, but the best guess was probably a suggestion that women tend to serve on more committees because boards strive diversify their make-up at the committee level.