Very nice, except... Rated 4 out of 5 stars
I love the simplicity: just the current temps with a hover for details.
The problem, for me, is that I am "forced" to having the panel open. If I hide the World Weather+ panel, when I hover over the status bar icon, I get an empty gray box.
I get the same result in Thuderbird 22.214.171.124 and Sunbird 0.7.
Oy, I really like the way you auto-hide the "Forecast" and "Options" links.