There's about 70 this month so far!! I don't really understand why they are registering, I mean they don't spam the forums or anything like that, the only thing they do is clutter up the community page.
It usually are crawlers that look for register forms, register themselves and do nothing. Worst case is they figure out how the forum works. May look into a way of stopping them..
edit: I have discussed with Dutchmega, but it seems the only thing for now is to let the bots 'invalidate'. They don't know how to install a client, so their account will be pruned anyway.