The update shows “bug fixes” as what it fixes.  It does not appear to really add any new features to the iPhone.  Some users are saying that speakerphone and play back of voice mail through speakerphone are louder.

This update does not appear to fix any Exchange Server email features or problems namely the deleting of emails on the iPhone still only marks the messages as being read in Outlook or Entrourage and not actually deleting them.

Users who have hacked their iPhone may see problems with their update and may be required to restore to factory default and then update.  Make sure to backup your photos on the phone prior to upgrading also as a precaution.