I'm currently using my own custom ROM, which is based on the 2nd leaked "official" Sprint rom that OMJ posted a week or two ago. If time syncronization is enabled under phone settings, then my timezone switches from Eastern (where I live) to Atlantic. However, if I disable time sync, and set the timezone back to Eastern, then everything works properly, including the calendar.
POSSIBLE SOLUTION:
From what I've read in Calku's thread, (
http://forum.ppcgeeks.com/showthread...44494&page=303) the issue is with the newer rilphone.dll, which was definitely upgraded between the 1st and 2nd leaked Sprint ROMS. I'm assuming that replacing the rilphone.dll with the sprint shipped ROM should fix this. I'll report back after I rebuild my ROM.