I'm not totally sure that this is the same problem, but...
Events that I enter on the Pre sync reliably to Google. Events that I enter on Google do not always sync to the Pre (yes, I've pressed "sync now" and waited for an hour, I'm not just being impatient). This can be solved by removing the google calender account from the Pre, adding it back, setting up all the colours for the different calendars etc... and then it will work for a day or two before failing again.
It's got to the stage that any time I add an event on Google I have to check the Pre to see whether it has appeared - which rather obliterates the point in having the sync to start with!
It was bad enough that Palm abandoned all PIM sync except for contacts & calendar, but now even that doesn't seem to work! It's driving me batty...
I'm on a Pre on O2 in the UK, WebOS 1.4.1.