Available in Beta.
Alien1974 is back at it again, this time with a theme that requires no additional setup. There is a widget available for the lockscreen, which is optional , and will turn off once your in the SpringBoard. Simply input your location or zip code for the weather, and don't forget to download Clock-Hide to make sure this works. And hey, it's iPhone 4 compatible!
I highly suggest you take a look at the discussion in our forums
to learn more and see a few more screenshots.