Rumor is that nader and paul have talked. You may be looking at this from the wrong direction.
LLS
Paul has not committed to supporting the Republican nominee. Indeed, he has sounded like he will not support the nominee unless he gets it.
To make 2008=1860, though, there would need to be two strong challengers to the "major" candidates, and I don't believe Nader OR Paul fill the bill. Furthermore, the left-wing moonbats know very well that Hillary is one of them.
If the GOP nominates a socon, then I think there will be a GOP liberal-RAT conservative "unity" ticket (think Bell-Everett), and there MAY be a right-wing Nader equivalent, as well (think Breckenridge). If the GOP nominates a liberal, there will be a conservative insurgency.
My main point is that the current party system and the increasingly entrepreneurial nature of running for office cannot stand the stresses that are going to be put on it between now and November 2008.