i'm sure once more and more people download this awesome little bw add-on, there will be tons of request for features and such.
some things i would suggest:
+add the option/shortcut to refresh the weather thru the popup
+create an "options" to configure pop-up size/font/color (kinda like berrypopup)
again, if this is meant to be just a small little add-on and nothing else, thats cool too