I'm on a PC.
Generally I had the iPad on and connected via the usb cable, started Calibre and it detected the device and I could 'send to device'. Calibre showed a column titled 'On device' and a green check mark next to any book in my library that was also on the iPad.
However, today I have installed 0.7.1 and now when I start Calibre it detects the device but can't get a list of books on the device or sync with it. Says there is an index out of range error in the driver.
I have tried uninstalling and going back to the previous versions of Calibre and these do not work now either!?
I will keep trying though as I don't want to check the iTunes option and duplicate all my files if I can get away with it..