Bddmed - 2:51 pm on May 19, 2007 (gmt 0)

It's not contextual. As it is site targeted.

I do see them on some pages, but only on second Adsense slots. Which I use very rarely anyway.

Performance is much lower than the primary slot. But you can expect that. If you're running only one Ad/page I would consider disabling them (you need to contact G for that).