The week before Rothstein's donation, RGA's annual conference was held in Crist's home state, in Miami (headlined, you may recall, by Sarah Palin). It's possible the Nov. 17, 2008 donation helped burnish Crist's reputation within RGA. Along with Rothstein's, a flurry of other Florida donations were entered for Nov. 17 in the group's post-election IRS filing (read it here).
Politicians around Florida of both parties, but particularly Republicans, were the beneficiaries of Rothstein's extraordinary largesse in the past five years. He, his family, and law firm distributed nearly $2 million to political causes since 2006, including $525,000 to the Florida GOP.
Rothstein is accused of setting up a side business to sell bogus legal settlements out of his law firm. While his 87-foot yacht and luxury car collection have been seized by authorities, he has not been criminally charged.
Late Update: The Palm Beach Post adds this useful context on the relationship between Crist and the RGA:
Gov. Charlie Crist hosted the conference, where he was hailed as one of the party's rising stars. In 2006, the RGA, led by then-Massachusetts Gov. Mitt Romney, donated $1 million to Crist's gubernatorial campaign.