Just saw this, updated on my tablet and tried it, everything seems to be working great after testing apart from a couple of small things, though may have been my fault as to get updated I had to uninstall CC and then re-install it for the update to be 'gotten' successfully.
1. The database was blank, so done the 'scan on connect' , then used the CSI (hehe. Content Server Intergration, that tickles me for some reason) and after dl'ing a few books connected to calibre through Wireless connection, that then said I had 2 copies of those dl'd books. Shouldn't have they been merged or picked up as being same versions.
2. (Also possibly related to my un/re-install) I used calibre while connected to remove the books from the device (300 odd books) and CC displayed the amount of books (No Grouping [# books]) and seem to be working away, but then froze, and I had to force close (I had to do that a couple of times).
Could/Would it be possible to display the busy/updating box while calibre does a delete operation?