There's a lot of wailing and gnashing of teeth going on on conservative blogs right now about the deal. Polipundit's top post right now is entitled "TREACHERY!". I ventured over to DailyKos and Democratic Underground to scope out the other side and the consensus there is that the deal means that Democrats have won this battle. So, are they right? Did the seven Republican Senators sell out their party? Did Frist lose badly?
It's far too early to tell. Both sides get something out of the deal right now. The right gets approval of three judges that give the left heartburn. The left gets to maintain the possibility of filibustering, which they desperately want for upcoming Supreme Court openings and can still stall on several of the Bush nominees. But nothing is really settled yet.
As with evaluating baseball trades you have to wait to see how things play out over time to know who "won" or "lost". Example: how will the term "extraordinary circumstances" get employed in the future? If Democrats claim that anyone "to the right of Karl Marx" is extreme and filibuster accordingly then the deal looks worse for the right. If the Pryor/Brown/Owens confirmations set a precedent for not filibustering qualified judges then it looks a lot better. Obviously a Supreme Court opening is the test here. I suspect that Democrats will call an opening on the High Court extraordinary circumstances no matter who is nominated.
The biggest thing that the deal does is avoid a dramatic showdown which would have very uncertain political fallout. If the constitutional option is executed (and it still could be in the future) and the Democrats respond by slowing down the Senate both sides would be gambling their political capital. The left has already painted such a rules change as an abuse of majority power. On the other side there's precedent (Gingrich's government shutdown) for the public looking unfavorablely on obstructionists. Most Senators are by nature conservative - in the sense of conserving their own jobs. It's not surprising at all that "moderates" from both parties would support this deal. They're the ones who are most likely to get hurt by any political fallout.
This deal marks the end of a major battle. But there's more coming and the outcome is far from certain.