One item that was left out of the conference committee version of the stimulus bill: the Van Hollen-Platts amendment from the House bill. That amendment would have granted whistleblower protection to federal workers and contractors, including those who report fraud and waste in—you guessed it—how the government spends stimulus money.
Zachary Roth at Talking Points Memo blames Sen. Susan Collins (R-Maine) for watering down the amendment in conference until it was eventually abandoned altogether. She apparently objected to the protection of whistleblowers who divulge classified information, though that language could easily have been removed.
If that's true, Collins deserves a lot of blame. But I'm also fairly certain that the Democrats have large majorities in both houses of Congress. If protecting federal whistleblowers who expose waste and abuse is any sort of priority for them, they had more than enough votes to keep the amendment in the bill.