I noticed that a recent edition of Engadget Podcast was sponsored by a "car oil" company. Bad for me for not remembering the name, but defintiely a more mainstream advertiser than the tech specific one I'd expect.
I guess the ads are probably being sold through the AOL Network so it might not be a targetted thing at all.
UPDATE (4/1/06): Ryan Block made a comment on the site to this post that their sponsor is Castrol. And that they have had other major sponsors like Best Buy and Nikon. I should have mentioned (sorry my mistake) the other two sponsors because it is true, and it also might have made it seem like this was Engadget's first big deal. It is not. They have definitely been a leader in drawing in podcast sponsorship.