Me and my wife's 3g iPhone also started to have the same problem all of a sudden. None of the apps we have installed launch and rebooting doesn't fix it 🙁
YES and here is the answer from Aaron Hostetler at the Genius Bar (Apple Store, Cincinnati, Kenwood Towne Center).
This is due to the handling of application memory. If you open and close a lot of apps this phenomenon will occur. Possible solution - turn off your iPhone then turn it back on
Anyway, when asked, he said he was 100% sure that this is what was going on.
I assume that this process (turning it off then one) clears the app memory.Seems to me that there should be a fix for 2.0 to handle memory more efficiently.
Me and my wife's 3g iPhone also started to have the same problem all of a sudden. None of the apps we have installed launch and rebooting doesn't fix it 🙁