The whole McCain-Feingold fiasco and other campaign finance "reform" laws are a convoluted mess. I recall reading last month that one of the reasons Kerry was suspending advertising for the month of August was that he knew the 527s would pick up the slack. The article stated that they had to spend their money before the 60 day blackout period hit. Of course, I may have misread the article or it could've been wrong.

Here's an article on Slate that states Internet ads aren't covered by McCain-Feingold.

The Bipartisan Campaign Finance Reform Act of 2002, popularly known as McCain-Feingold, had two big goals: stopping the flow of unlimited soft-money donations from corporations, individuals, and unions to political parties; and preventing corporations and unions (and groups funded by corporations and unions) from broadcasting so-called "issue ads" on television and radio within 30 days of a primary and 60 days of the general election. The Internet makes it possible to subvert both goals, however, and that's where you come in, Mr. Soros.

This paragraph suggests that 527s may not be affected by McCain-Feingold, but I'm not sure.