It pisses me off when people say “Thank you” in public forums, without making any other useful comment.
I get lots of e-mail, I really don't need to read peoples public “Thank you” letters.
I'm all for saying “Thanks” if you have a follow on question, or something useful to add. Otherwise, keep the praise off list.
I didn't used to think like this. I used to be cool about it. But I've just had to read one too many thank you note lately, and it really is nothing more than noise.
(not that I mind noise, as long as it's in the right forum ;)