Had a comment spam appear which had only the one link (with the word "poker" among others). Interesting - clearly a spam. (Because I get emailed when there's a new comment, I picked it up right away.)
So people trying to spam WordPress blogs may have realised that they can't use multiple links.
One other thing that I notice with comment spam: it's always made to old entries. Never to the newest ones, presumably because you'd be more likely to be told about those made to new ones, or notice it yourself.
I think the list of spam words is going to have to be enlarged, if one is going to leave it feasible for people to leave comments without registering.
Perhaps for 1.3 (or 1.4??) a system whereby "block comments on posts older than.... " ?