Apple released an update for the OS for the iPhone on August 19, 2008 (version 2.02). I have had this update for about 24 hours now and found that some of the applications that I had installed - would not load up anymore. Clicking on the application's icon would result in a new window in which the apps looked like they were trying to open. But almost instantly - the apps would crash and I would be returned to the home screen.
I then installed a couple of new apps from the iPhone App store and those were working correctly. So I thought that maybe the update had messed up some settings for the applications that I had installed before running the update. So I uninstalled all the applications that I had installed before the update. (To do this - keep your finger down on one of the app's icons on the home screen. After a couple of seconds - they icons will start wiggling. All applications that can be removed will have a small cross at the top left corner of the icon. Tap the cross to uninstall the application.)
After you uninstall all the apps that don't work anymore - reinstall them. And they should work like before.
Important : When most apps get uninstalled - all the files that were used by the app will also be deleted. So dont do the above step until you have reviewed the data that each app stores and backed up the important ones.
List of apps that failed after updating to v2.02 - Facebook, Google, TipStar. All of them work fine now after being reinstalled.
Update : v2.02 seems to be a LOT more stable. Before I used to experience app failures atleast once a day. Since I installed v2.02, I havent had one app behaving badly. Wooo! Hooo!