Sen. Robert Byrd (D-W.Va.) is not doing well health wise.
At 90 years old, he needs help walking, and there are suggestions that he is no longer physically able to run the appropriations committee, so there are discussions about moving him aside.
At this point, it is just talk, and any move would set up a battle for who would head the powerful committee, so my guess is that nothing will be done until 2008.
Unfortunately, he was re-elected in 2006, so this will have to be sorted out sooner or later.