You should be able to get your books without plugging in by using your browser. You can put the URL of the stores you use frequently into your favorites. The Sony store is on the main menu. If you use Calibre you can load your books wirelessly from Calibre by using the correct ip address in this format:
http://192.168.X.XXX:8080/browse
The ip address is your local address, I don't have a mac so can't tell you how to find it but you could google it.
Sorry, in my previous post I assumed you had a PC...