Blog spam - sad state of affair

For the first two months or so since I opened my blog site on March 7th, 2006,
I had no spam on my blog.  Then suddenly one day, right after my trip to
the 2nd Webloggin Ecosystme Workshop where my student presented our paper on
"Collaborative blog spam filtering using adaptive percolation search,"
I started to get spams on my blog.  Today, I counted 60 spams on my mere 12 postings. 
They are doubly annoying, as they annoy visitors to my blog.  I deleted them all.  Now I wonder if I should still keep the comment area open to public.
For the data collection purpose, I will keep it open for the time being.

We're currently trying to improve our proposed filtering scheme to make it practical to implement in TatterTools, the blog system I am currently using.  We'd better hurry for my own sake.