Let me risk a lit prognostication here. I predict that:
1. Frist will call for a vote on the nuclear option.
2. The vote will fail.
Frist has put himself into a corner on the nuclear option. He knows Reid won't budge on using the filibuster to block Bush judicial nominees. But he also knows that the Republican base simply won't accept anything less than a full effort on his part to get them through, even if that means destroying 200 years of Senate tradition. He has to call for the vote if he is to have ANY chance at the nomination in 2008. If he yields on this point they will scream for his scalp.
But, if Frist had the votes, he would have called for it already. The longer he waits the more bad PR the Republicans suffer. Harry Reid knows this also (he held a conference call with bloggers earlier this week in which he apparently said as much).
Normally it would be bad form for a leader to call for a vote when they don't have the votes. No one wants to have a loss on their record and legislators prefer not to go on the record for a lost cause. But the only option left to Frist is to call for the vote even though he knows he will lose. That way he can at least tell his base that he didn't back down. And he can throw to the wolves the few Republicans that vote against it.
And this would be the best of all possible outcomes for the Democrats. A negotiated settlement that results in no vote would still be a victory, of sorts. But an on-the-record defeat would be even better, especially since the Democrats could then use the official votes against those who voted for it.