With the 3.08 Fifrefox 2.0 can use the 'subscribe now' function to simply launch feed reader with the feed address pasted yet into 'add now' textbox of the reader.
With 3.09 this function doesn't work no more. Simply, clicking subscribe now, with feedreader.exe won't do nothing. Sigh, it was very usefull.
I tryed on 3 differente machines but with every pc this problem happens.