Some first generation iPhone folks with PWNAGE 2.0 are noticing a bug, when launching applications installed from the App Store, the app would launch for a second or two and crashes back to Home Screen. The fix seems to be easy enough, simply re-PWN it.
I went through the process of re-pwning a new custom firmware, this time, I built the custom firmware by answering "yes" to the question: Have you Pwn'd before? Once built, simply connect your iPhone to iTunes and hold down "option key (mac)" and click "restore" and select the freshly built firmware. Because you've pwn'd it once, you no longer need to boot into DFU mode first to restore the newly built firmware.
The apps seem to work fine after that!
Update 7/25/08: This happened again to me, but I am onto something. It appears that the first set of applications I downloaded reside in iTunes, this somehow conflicts with the same set of apps I re-downloaded onto the iPhone itself. To get a clean scratch, I deleted all apps off of my iTunes, sync with iPhone to remove all apps. Downloaded all the apps I wanted to iTunes again, then sync'd it with the iPhone. So far so good.
Update 7/26/08: The iPhone Apps crashing issue appears to be isolated from PWNAGE. Looks like the general iPhone/iTunes Apps situation is a big mess. Other people are reporting the iPhone Apps crashing as well as another issue (I also noticed it earlier today) that iTunes is not sync'ing up well with iPhone's applications. It appears that iPhones can get application updates without problems but iTunes is not seeing the same updates. Even if you updated your applications via iPhone, it will not sync back to your iTunes library. As for me, because of this complicated update situation, even on an all-stock 3G, non-PWNED iPhone, it is yielding some sync' errors with iTunes.