GCALDaemon is an OS-independent Java program that offers two-way synchronization between Google Calendar and various iCalendar compatible calendar applications.
The problem with the official version is a nasty bug that disallow synchronization of Repeating appointments Rendering this fine program unusable for most. So I wrote a patch, and as it could be useful for others I post the resulting program here
sorry no windows version: I wouldn't now how to compile it