If you have a Samsung Vibrant running CyanongenMod, then you probably want to flash a a stock-based ROM double-quick. Why? Because you can't call 911 while running CM on this particular device. Sure, you may not remember the last time you had to call 911 (if ever), but can you imagine what would happen if you were in a situation where you needed to call 911 and couldn't?
For this exact reason, the CM team has decided to drop support for the Vibrant.