First of all, I have not been able to get Google's synchronization tool to work. There are wide reports of this problem, and most likely it is that the fine folks at GOOG did not anticipate everyone with an S60 trying to sync their Gmail on the same day. So great is the demand.
However there are some other options:
- Googasync - supports one calendar, slow, but works. The drawback, costs $22.90 USD. There isn't an email address on the entire website (which consists of one page and a buy button). After you purchase the item, however, it is possible to correspond with the developer. Nice fellow. I experienced problems with this item once I installed the full-paid version. The Demo worked fine.
- Nuevasync - uses the Mail for Exchange application and supports up to 11 calendars, acts as a relay between Google and the S60.
All the other items I found either wouldn't install because of signing errors or had too many other issues, such as dates and times changed on the phone.