http://google.com/news?um=1&q=google (with an extra "um=1" parameter)

Blue-ish like the normal web search.

No don't think so. I have had it for a while

I think it was released at the same time as this "View all web results" feature:

http://blogoscoped.com/forum/88631.html

The addition of that parameter seems to be totally random though. I'm not sure if you've noticed, but it also changes the logos to be a simple "Google" logo too.

It also works for Blog Search (which is where I first noticed it), Book Search, Image Search and Patent Search.