Today I've found a nice iOS warning every second time I start up my application on the device: "WARNING! Creating precompiled collator because collator is out of date. This is expensive!". Apple's programmers are informative about the consequences but not that much about the causes. I don't get any other errors or warning.
Google also can hardly help to comprehend what's happening. There are only some anecdotal evidences that it happens on iOS 4.2.1 - same as my device is running. Some other sources suggest that the warning is due to framework bug and I will get rid of it tomorrow after iOS 4.3 installation (or iPhone SDK 4.3 setup).