Last night I was helping pudge fix his Mac::* modules to work on OSX/Intel. One of the tests he got me to do was to create a calendar entry next week and switch focus to iCal.
Only the bug was in endian conversion of a number, so instead of getting a date (as epoch seconds) next week, we got one back as epoch seconds in about 10,000 years from now.
iCal kindly obliged, only it did so dumbly - seemingly creating memory space for all the dates from now until 10,000 years in the future. Used up all my ram. Crashed iCal, knocked me off the net, had to restart Mail.app and Safari too to recover some memory.
What fun. (I see the bug is now fixed and on CPAN).