I was a Community Moderator for Scratch for a couple years, and i'm now doing mentoring, and of course my admin position on their wiki. Other than that, i'm not officially associated.
I highly recommend using Scratch for introductory programming (or even not-so-introductory). Of course, i may be slightly biased. ;) If you do, don't forget to check the wiki for answers to questions you might have. ;)