I don't know a lot about it other than from anecdotal evidence here on the OH forums. It DOES seem to be effective for some. I know Carnie Wilson just did it but don't know what her results have been.
On OH, the most successful BOB I know of is Liza Beezee (I think that's her name - I will check my friends list after I post this and correct it if it's wrong. She had a lot of success with the procedure and seems to be very knowledgable about it.
The downside is that she is the only one that I know of specifically that has had success. I've seen many more stories of the procedure failing. I can see how it would work physiologically and ideally I suppose, but stories about the band are just so negative and plentiful that I would probably think and re-think and re-think again before I did this.
You might check the revisions board. Sometimes there is info on this over there.
Best of luck to you on your journey=)
edited to add Lisa's profile:
http://www.obesityhelp.com/member/lisabeezee/