I wish there was something like this two years ago when I posted in the rideshare section of craigslist offering a ride from nyc to Boston. If Zimride were around then I woul never have given that couple's massage sex therapist who's father passed away earlier that week and had to run away from stuff to nyc for a few days.
I can see them teaming up with zipcar for people who are going away/back home for the weekend and want to cut down on expenses. Fun stuff.