Let's hope the lack of posts in the bugs-section is a proof for the stability of Rocks'n'Diamonds (and not for the lack of beta-testers)
About the silence in general: I have no idea. I can only speak for myself, when I say that I don't have much time for playing R'n'D lately. So I also haven't much comlplaints or ideas about it either :/
On the other hand there's a blessed absence of troublemakers so that there's not much moderator work either.