I'll re-bump as I just purchased my first pair of VFF's a few weeks ago.
I was originally skeptical of the minimalist running movement. Everyone I talked to seemed to scoff and brush it off as a "hippie fad" that would soon pass. After a few weeks of wearing my VFF's, I can easily say I've never enjoyed running more than I do now.
I decided to buy the KSO's because I like the idea of "keeping stuff out" of my shoes and they seem to have the simplest strap system. Excellent choice so far; these are the style I would recommend if you want the VFF that will do it all. I wish I had waited a bit longer for the Bikilas, but who knows how long until those are widely available.
Anyway, as previously stated, you definitely need to ease into wearing these things for running. I spend most of my leisure time barefoot already, but that wasn't nearly enough to prepare my muscles for barefoot running. Expect some sore calves at first!
I did TONS of research leading up to my VFF transition and now I don't think I can ever look back. I'd recommend
Vibram Five Fingers News, Reviews, and Fan Forums - Birthday Shoes as a starting point. They have a lot of great articles and reviews to get anyone interested in barefoot/minimalist running.
I'm open to suggestions and techniques from anyone else who's made the transition, looking forward to hearing them. Happy barefooting!