Why does iTunes freeze for about 30 seconds when plugging in my iPhone 3G?

Every time I have iTunes running (on OS X) and plugin my 16GB iPhone 3G it'll freeze for about 30 seconds or more with just the "spinning beachball" cursor (music remains playing but the interface is unresponsive and media keys don't respond)

I have no idea why it happens as, although there's a noticeable delay, the iPhones in the Apple Stores and my friend's iPhone doesn't freeze iTunes: I originally setup the iPhone in iTunes on Windows and later bought a Mac and re-synced it from there, but - as far as I can remember - the freezing happened on Windows too.

Pulling out the iPhone during the freezing immediately makes iTunes responsive again but shows an error message about being unable to communicate with the device; I'm thinking it's something weird about my iPhone.

I used to just ignore it but now it's a tad frustrating especially as I'm constantly docking and undocking my iPhone during app development: anybody had this problem or knows why it might be happening?