Notices

You could write a simple python daemon to listen for the DBUS signals that are emitted on events like incoming call/sms/etc and then use the calendar API to fill these to your local N900 calendar (if you have working calendar sync) or just do whatever you want with them.

It shouldn't be all that hard to do, a prototype can be coded in an evening, adding polish would probably take a weekend.

So, help yourself. python is easy to learn and this forum has examples for listening to the signals.