I know this isn't a feature, to my knowledge, but would it be possible to have a central database running calibre, and have client versions synching to a server?
The reason I ask, is that I have calibre installed on a Macbook Pro, a Macbook, my Windows 7 machine I use as an office and gaming machine, and my linux server which will eventually be running all sorts of services using ESXi.
I would LOVE to have calibre clients on either of the Macbooks and the Windows 7 machine to have access to a calibre install with all my recent additions, news feeds, etc.
My kobo needs physical access to calibre to transfer the files over, so it becomes cumbersome for me to bring my kobo downstairs (where I don't hang out most often) when I could simply connect it to either of my Macbooks and then transfer the content I have on my linux server.
I just like trying to centralize things because I'm geeky that way! Hell, I don't even go downstairs to turn on either of my computers, I use WoLAN! hehehe