Well you are not alone. Even big Typepad bloggers like Seth Godin are now getting hit, as the spammers have found a way around the “no follow” implementation on the service.
Spamroll gets trackback spammed on a regular basis, but while “no follow” is ever present and running, I still take the time to clean up the garbage, in bulk, fairly often. Of course, every time I do so, I wonder why anyone with their head screwed on straight would ever want to spam such a good for nothing site anyway! He he.