EMP1  for everyone that is trying to get the "file not found" error fixed you can fix it yourself.

browse to pandora.wdgt file and right click and select show package contents. Then open Pandora.html in a text editor, and change "tuner_8_8_0_0_pandora_mini.swf" to "tuner_8_8_0_1_pandora_mini.swf".

save and install the widget and your done.

hopefully the author will offer a more robust solution so we will not have to keep modifying/upgrading the widget everytime pandora changes the filename/version. Even if not, it is still a great widget and only a minor annoyance that you can fix yourself.  
(Version 1.0.6)