I'm experiencing multiple issues with Press This on Firefox 16, Mac and Windows.
First of all, the Tags function is broken. I can't add tags and the "Choose from the most used tags" link does not do anything. Also, the expand arrow on the Categories and Tags boxes does nothing. I've been saving as draft and going into the Dashboard to add the tags before publishing. This is fairly recent.
Also, is there a setting in Chrome that prevents Press This from working? I was hoping to check it against Firefox on both platforms but it doesn't pop up the window on Chrome (Mac and Windows).