Like most iPhone OS updates, version 2.0.1 will trigger an update to carrier settings. However, under iPhone OS 2.0.1, when iTunes attempts to perform the carrier update, users may receive an error message, and the process may repeat itself every time the device is synced.
The other problem is that customers of carriers like Vodafone, which are offering unlocked phones, are experiencing problems connecting back to company's services. Following the update users in these cases are receiving a "0xE8000001" error message on both Windows and Mac versions of iTunes.
Reports of this issue are coming in from Vodafone, Telstra and Optus in Australia, Softbank in Japan and others. So far there, no AT&T customers are reporting the issue. In any case, it appears that a "Restore" process sometimes resolves the problem:
Connect your iPhone to your Mac or PC and, in iTunes, click the Restore button under the Summary tab. Restoring the phone will erase contacts, calendars, photos and other data on the phone, but will restore automatically backed-up information including text messages, notes, call history, contact favorites, sound settings, widget settings, etc.