I've got 2 problems with weather indicator in Ubuntu 11.10 with unity.
1) The weather indicator doesn't launch after starting up the system.
2) The icon which is supposed to show clouds or a sun etc. shows a question mark insted.
For the first problem, just add it to your startup applications. Click the power icon (top right of your screen) and choose 'Startup applications'. Add one with the command
For the second problem, this is a known intermittent bug with Google. Switch to Yahoo! as the source in the preferences. You right-click on the indicator to access the preferences dialogue.