Adsense isn't exactly search-related ads, but it is tied in with keyword ads. Google is now venturing into blog advertising. Apparently they saw that a lot of bloggers were putting up non-Google ads, so they figure it's worth a shot. The new service is being tested by a few advertisers and should be available to the rest of us within a few weeks (still in beta, of course).
It looks like Google is looking to become a super-sized ad network. I wonder if they'll forget their roots and move away from their core expertise of search like so many search engines have done before them. They already seem to be losing their edge--at least in terms of quality of search. Can you blame them for trying to horizons a little bit? Or will this move lead them astray?