I've downloaded and installed PocketMac 4.0 and am having the same issue across several clients - iCal just won't synchronize.
Contacts are synchronizing from Address Book, but every time we try and sync Calendar, it seems there is a different result.

Sometimes the Blackberry shuts off, red light comes on and then the unit restarts after the USB is unplugged.
Sometimes the Calendar says it successfully synchronized, but nothing shows up on the BB side.
Sometimes the Calendar appears to be synchronizing from within PocketMac, but nothing on the BB indicates that it is, and no data is present on the BB.

We've tried resetting, wiping the handset, re-installing the software, tried different cords, different machines - PowerPC, Intel, etc etc. iCal just won't synchronize.
Used the Purge utilities, un-installed, re-installed - Even archive and installed the operating system. No luck.

Spent about 6 hours on it tonight. I have to say, I'm completely frustrated and my clients are ready to throw their Macs and their BBs out of the window.
Any thoughts?

We're using OS X 10.4.8, BB Pearl and Pocket Mac 4.0 on G4 Powerbook.

The unit can successfully sync on a PC.

The previous PocketMac version sync'd both contacts and calendars well with our 7100's. My wife and I would sync our BB's and let .Mac automatically the two computers pretty much realtime. Upon the next BB sync, fully synch'd calendars and contact on both BBs and Macs.

Our experience with PM 4.0 and the 8100 has been frustrating as well. PocketMac seems to sync contacts well in Entourage with a single Mac. However, when two Macs sychronize with .Mac, we have 2-4 copies of each contact created on the BBs (one from each BB and one from each Mac). We've tried to debug but may ultimately fall back to a previous backup and not reconcile between machines with .Mac (something appears to have changed with PM and the new PM 4.0).

Worse, synching with PM 4.0 to update iCal and Entourage calendar seems to work with one Mac. However, when two Macs Sync via .mac, changes are only transferred to iCal (and are not transferred in Entourage) despite setting preferences for both. With the previous PM, we had perfect calendar synching between 2 Macs and 2 BBs - something clearly changed with PM 4.0. We're trying to figure out what is actually going on - iCal appears to the correct synch information - albeit multiple copies of each calendar event (similar to contact issue above - appointment from BB1, same from BB2, same from Mac1, same from Mac2). It has been frustrating given that 7100 synch worked so well the previous PM verison and .mac.

Maybe someone else with a similar configuration has had a better experience and might enlighten us to what might be wrong. Otherwise, we could fallback and use iCal and Mail (and not Entourage) and see if synch will occur correctly between 2 machines and BBs via .Mac. If not, the usefullness of .Mac will diminish quickly for us.