It seems that Apple has pushed out the iPhone OS 3.1.3 update. This update has a few behind the scenes performance related updates, aimed at 3GS battery life and 3rd party vendor apps.   Third party apps were not launching and working intermittently from reports, and Apple has addressed that with this release.

To update your iPhone plug it in, and start iTunes (you know the drill).  Click the “Check for updates” button and the upgrade will run.  Its always a good idea to back up your phone in iTunes before upgrading.

Let me know if you notice something else in the comments.

Colin