Recurring events are not really a challenge per se (thanks to the limitation of N900 calendar...see below). In fact it's just a relatively easy piece of code to be added. I left it behind for the moment because I wanted to have a stable solution for simple events first.

The only problem I can foresee: the N900 calendar program is very limited with recurring events: you cannot insert exceptions in a recurring rule, so recurring events with exceptions transferred from Google to the N900 will not reflect the real state of the calendar. This is the only issue I see so far.