You haven't stated where or how you'll be posting/publishing your compilation.

A release is a legal document--a first name could be anyone.

On my site, I refer to info-providers by jointly approved online names. I respect their need for privacy, however, in my files HERE, I've got the releases.

Minimally, if you're publishing your compilation online, you can provide the urls for discussions.

I kind of found out my answer on CNN the other day when they interviewed two guys who wrote a book called 'Overheard in New York'. They compiled a book of things they overheard people saying in NY. They didn't have to get permission because they didn't use names. As I'm only going to use first names I don't think I have to get permission either. I can always change the name to protect identities, but since I am not editing anything controversial I don't really think that will be necessary.
Also, what I'm editing has nothing to do with the web.

Good luck with your compilation ;-)

As a former photojournalist (a bit different since the image definitely is of a unique individual, and, so, more traceable), I'll say that you can cover your bases in future interviews with a disclaimer that says you may want to publish the answers in the future, and by replying, the interviewee gives you those rights.

I think it fair to be upfront andgive someone a heads up on your use, and let them reply accordingly, rather than risk someone getting pissed off down the line. Legally, if they posted online, it's probaly public domain. But, you are gaining by utilizing their words for publication, so should be upfront about that, to my mind.