Possibly caching of data and a "last updated" label. Say I have internet on Monday, it downloads information for the week and saves it off. Then, if I don't have internet until wednesday, it still has the last good info, but the label says that I last synced on whatever date.
Also, will the plugin be constantly polling in the background, or only when you enter the weather skin? Ideally I'd like it to either automatically do it on skin start or have a command to sync the weather. That way when I get in my car in the morning, and get wifi from my apartment, I don't have to go into the weather skin to update the information.