FYI - I am in Tennessee, and my internet connectivity is spotty at best... sorry I haven't been more responsive to all the recent activity....
The spam problem in the Community has been pretty narrowly focused. The overwhelming majority of it comes not from comments but from new accounts being created and then spam blog posts being created immediately thereafter on those accounts. These new posts show up in the activity stream, and thus are more publicly noticeable than usual.
There has already been for some time a combination captcha/question/known-spammer-database check on new signups, but some new signups have been defeating all these barriers (I assume by using human "bots" to create the accounts, then turning over to the bot-lords to spawn posts that attempt to appear as legitimate blog posts).
There is a "flag as spam" button now available, and you can access the flagged posts in the Moderation menu of Buddypress.
It is better to mark a user as spammer than to delete the account, as that way the system gets trained, and they are prevented from simply signing up with the same credentials again. Once they've been marked, their blog is suspended and they can't create any new content - they are essentially frozen.
I've even setup the registration page to be a randomized URL every few hours so that spambots can't find the door...
I'm still working on locking out completely manual signups so that users must create accounts with facebook.
thanks for your help and patience...
- ic