Google claims it acts in the same manner as a news server. However . . .

I once accidentally made a public posting on a newsgroup that was intended to be a private email. Google gave me around about removing it from google mail. I sent a letter on letterhead to their legal apartment asserting copyright infringement and ending with three words: "Just try me."

The post was removed the same day the letter was received.

As far as copyright law and reproduced posts, I've explained this recently and in detail on another thread -- it's too late to look for it now, but do a search on my name and you'll find it.