I tried the method posted above:

- download a trial version of MS Office (standard will do)
- sync iphone/touch calendar with Outlook via options in itunes
- open Outlook and save calendar (creates .ics file)
- login to Google and import calendar file (bottom left, "Add")

And it just deletes all calendar entries and starts again... this is on 4.0 so maybe thats why... any idea how I can do it?