Sponsored tags suck.
You're half a step away from having flashing animated gifs, scrolling marquees and those terrible ‘Free Forever’ ads. (Oh, and to all those people whose knickers just got in a knot, it's called hyperbole ;b)
I think it comes across as visually jarring, seems like a clumsy grab-for-cash, add zero value to the question/answer and hinders usability by breaking the consistency rule.
It's actually a bit disappointing Jeff because in the past you have had quite a strong and honourable stance when it comes to advertising (See How To Advertise on Your Blog Without (Completely) Selling Out). I don’t know what your motivations are for expanding the SO family advertising in such a way, but in my opinion, the credibility, design and usability are all suffering as a result.
Please keep the advertising out of the content, our eyes will thank you for it.
@Jeff: It's your site and you can do whatever you want with it and I sincerely (for real) hope that you and Joel (and Geoff and Jarrod) make bucket loads of money out of it. I consider SO to be the best programming site out there and I consider you to be 'the good guys'.
But the content on the site comes from us, the users, so we do feel as if we have some right to at least comment and provide feedback on the direction of the site.
You don't have to heed the feedback, but due to the source of the content on the site, at least listening to the feedback (without getting cranky and sarcastic) seems like the right thing for you to do.
Yes, we can go to some other site if we don't like this one, but we DO like this one, and it sucks when it moves in a direction that makes us like it less.
And this is why I think this style of advertising has caused such a reaction amongst your users. It is pushing the boundaries (which are grey and muddy by the way), and we are just letting you know that.