Depends on which day you ask us... 

Actually you can get a U.S. Support Ribbon avatar right now.  Other than that, right now other things have taken precedence over the avatars - you're actually one of the first people to ask.
So basically at this point only the moderators have them.  That is also subject to change.  (meaning once I finish up a few other things I may be adding some avatars for regular members)
