I just saw this at the Google Blog and gave it a try. What a cool idea - this makes finding out the current weather conditions easier than ever. Check out the attention to detail in the formatting of the results - very simple and polished:
Searching for weather, by web or phone
As a kid, I would stare for hours at repetitious weather reports on TV. Boring, you say? Not to me - I love weather. And since I've worked here, I've wondered why Google doesn't do weather. It seemed like a perfect 20% project for me, so now I'm pleased to report that you can get current conditions and a forecast by typing [weather Chicago], or whatever your U.S. location is (zipcodes are also fair game). If you prefer, use Google SMS to send a text message to the U.S. five digit shortcode 46645 (GOOGL on most mobile phones) followed by your meteorological query.
Ben Sigelman
Software Engineer