Some Apple users who have updated to iOS 4.3.3 have begun reporting that they are experiencing issues regarding data connectivity over Wi-Fi.
The issue, at least from reports, is that the device is not retrieving the proper IP address settings when connected to a local network. There are some potential options for fixing the issue, including restoring the phone, resetting the network, and even doing a hard reset. None of these options worked reliably for any user. One user did contact Apple and they told him to bring his phone to the Apple store and get it swapped out.
I am not sure what is ultimately causing this issue. However, since this only began appearing after users upgraded to 4.3.3, it is most likely an issue that is caused by the recent software update. But it is hard to say, since as of this writing, Apple has not acknowledged this issue.