From Craig Hunter:
Wx displays detailed US weather info and maps on an iPhone or iPod touch, taking its settings from the full featured Wx weather app on Mac OS X. Heres how it works: set up weather locations and maps on your Mac in Wx, then export a special Wx bookmark to Safari. Connect your iPhone or iPod touch to your computer, sync your bookmarks, and thats it. Just tap the new Wx bookmark in Safari on your iPhone or iPod touch to access your own custom weather center anywhere you go.
Like Wx on a Mac, the mobile version of Wx will display weather for up to 20 locations and up to 20 weather maps. Each location has a section for current weather, alerts, radar, and a comprehensive zone forecast. Radar and map views can be zoomed to full resolution and panned with the touch-screen input gestures available on iPhone and iPod touch.