In the 109th Congress the Republican majority let Duke Cunningham remain on the Appropriations Committee right up until his guilty plea, and didn't remove Bob Ney as Chair of the Admin Committee until many months after charges first surfaced; worst of all, GOP leadership tried to change one of the only formal rules in place, the aforementioned prohibition on party leaders under indictment, to allow Tom DeLay to remain in power.  Rep. Jerry Lewis (R-CA) is the ranking member on the Appropriations Committee, even though he's under federal investigation for misuse of his position as Chair of that panel.  According to Roll Call, other Republicans who have retained committee positions are Reps. Gary Miller (R-CA) and Ken Calvert (R-CA).

And it's not like Democrats are clear on this issue, either.  Most notably, Rep. William Jefferson (D-LA) was allowed to serve on the Ways and Means Committee until his Congressional ofice was raided by the FBI, even though he'd been under federal investigation for bribery for a long time before.  He still serves on the Small Business Committee.  Then there's Rep. Alan Mollohan (D-WV), who stepped down from the House Ethics Committee (you think?) amid questions of his own ethical violations, but continues to serve on the Appropriations Committee.

Republican leadership of late has given the impression that there's an attitude-shift at work - according to Minority Leader John Boehner (R-OH), a "clear likelihood of serious transgressions will lead to suspension from important committee positions. Guilt will lead to immediate and severe consequences."

Well, that's a good start, I guess.  But it's still not a standard rule they can either follow or be held accountable to.  As the Roll Call editorial staff aptly puts it, it's "we'll know it when we see it" - and that's just not good enough.