So far, people listing their occupation as "law professor" have donated $18,365 to Republicans, and $149,542 to Democrats. Those who list their occupation as "professor of law" have donated $500 to Republicans, and $34,565 to Democrats.
A caution on extrapolating from those data points: on the one hand, the Democratic candidates in general [that is, from the public at large] have raised much more money than have the Republicans; on the other hand, given the much smaller number of Republican law professors, donating to a campaign is more likely to help get a Republican professor a future political appointment, perhaps giving an extra incentive to some Republicans to donate.
Ninety-seven self-described law professors have donated to Barack Obama, only thirty-five to Hillary Clinton. Fred Thompson is the Republican favorite, with seven donors, compared to Giuliani's five and McCain's four. Mike Huckabee, Ron Paul, and Dennis Kucinich have none.
Note that this is not even close to the complete universe of law professor donations. Many, perhaps most, law professors list their occupation as professor, not law professor. At Harvard, for example, Dershowitz, Elhauge, and Singer call themselves "law professor," but Mack, Stone, Tushnet, Wilkins refer to themselves simply as "professors," Tribe lists his occupation as "attorney," and Ogletree doesn't list an occupation. Even more obscure are Michelman and Parker, who don't use the word "law" in describing either their profession ("professor") or their employer ("Harvard University"). Nevertheless, the list of "law professor" and "professor of law" donations is likely representative of the greater universe of law professor donations.
A few other items I noticed: Drew Days, Bill Clinton's Solicitor General, contributed to Tom Vilsack's [???] campaign, but not to Hillary's. Professors sometimes considered "conservative," at least by legal academy standards, such as former Yale dean Tony Kronman, Harvard's Einer Elhauge, and Cardozo's Marci Hamilton, are Barack Obama contributors. Stanford Dean Larry Kramer has donated to both Clinton and Obama.
Plus, a non-law professor tidbit: Colin Powell is backing McCain. And an inside-baseball libertarian tidbit: Lew Rockwell, former Ron Paul chief of staff and president of the Ludwig von Mises Institute, who is perhaps the most vocal and vehement Ron Paul supporter in the blogosphere and perhaps the world, apparently hasn't given the good doctor at least $200 (the FEC reporting threshold), if anything.