That is great.
Although it is VERY hard to find. Double clicking normally opens the document. I have to right-click and - the menu still open - double click in order to edit. (Ubuntu 12.04 with Calibre 0.8.38)
I would love a "edit multiple" (select multiple, add them to a single collection).
BTW: I just saw why I should import all my books to Calibre. I changed an collection and unplugged my device without ejecting it. I got an error message on the device saying something about faulty internal memory. OK brought a "Formatting intermal memory ...". And then, everything was gone. Not even the chance to repair something.
Luckily I imported almost everything into Calibre just yesterday.