Roy, I don't know if Telligent has installed ReverseDOS on Weblogs.asp.net but you can override Community Server spam blocker Add-on settings in your blog control panel (I hope spammers use constant names in comments).
On the other hand we (some CS folks) are working on a collection of CSModules. One of them is Akismet CSModule which is being done by Thomas Freudenberg and can block huge amount of spams. We'll ask Telligent to install it on this server as well (if they haven't installed it before because I guess Scott Watermasysk had same Add-on for CS himself).