Business Week has an article about the move of many companies to list their shares on the London Stock Exchange in a move to avoid the difficulties of Sarbanes-Oxley compliance. It seems listing in the U.S. no longer carries the cachet it once did, and the burdens of Sarbanes-Oxley compliance have discouraged many companies from listing in the U.S.
The NYSE and NASDAQ are blaming Sarbanes-Oxley, but according to the article, the move to other markets may have as much to do with the fact that other markets have developed into deep capital markets in the past few years. In 2005, according to the article, only 1 of the top 25 IPOs was in the U.S. This was a sharp drop from prior years.