In my opinion, the new taskbar or Superbar in Windows 7 is probably the best feature in the operating system. Jumplists and lively taskbar buttons have really given developers opportunities to create excellent widgets, even better than what you can get with the Windows Gadgets platform. Some widgets we have covered in the past include a Gmail notifier, 7Stacks, StandaloneStack and Taskbar Meters. Lee Matthews from Download Squad has covered a taskbar widget called WeatherBar which puts weather information in the taskbar. WeatherBar uses taskbar overlays, jumplists, and taskbar button progress bar to show information at just a glance.
I love this app and have been using it regularly, but there are a few issues such as the lack of an option to switch between Fahrenheit and Celsius. It shows temperatures in just Fahrenheit in the jumplist. Another feature request would be to make the taskbar preview a little more useful by showing some useful information in it instead of the app preview (see Gmail notifier for an example).
Otherwise, this is a must have application if you like to stay up to date with the weather 24/7 and have enough space on your taskbar for a widget.