The micro-blogging service Twitter was rife with comments from adopters whose update process timed out in the middle, or referred them to Apple's iTunes store to complete the update process only to find the store was overrun and the network could not be accessed.

A sampling of comments:

* "2.0 is a trainwreck for me. It won't sync to iTunes. Now my phone is bricked to to timeout."

* "iphone 2.0 i hate u. u bricked my phone."

* "having mucho problems updating my iphone to 2.0, after a crash, restore, then attempted update...appears to be completely bricked"

* "itunes music store failed in my 2.0 update. bricked my damn phone. waiting for it to come back up."

* "Nice. Apple's firmware update just bricked my phone."

* "so far - not good. iphone 2.0 upgrade couldnt complete, having to restore my iphone"

* "I fear I may have temporarily bricked my phone; no itunes store no update, apparently"

Here, in the Test Center lab, an iPhone upgrade to 2.0 software resulted in much the same: a 45-minute process of downloading the firmware and then watching as iTunes and the iPhone entered into a process of backing up, installing, backing up, restoring to factory defaults - - followed by a message advising to keep the iPhone plugged in while it accessed the iTunes Store. And then everything stopped and a message appeared: "We could not complete your iTunes Store request. The network connection timed out."

With more than six million iPhone holders set to upgrade today, Apple's servers may be a bit overtaxed.