I am not sure if this helps: but on the iPhone you can link in the google calendar via caldav. 2 way sync works pretty well - haven't got any issues yet.

So you have contacts via syncml, calendar via caldav and mail via imap. At least I am doing it that way on the iPhone (and company stuff via the exchange client)

edit: sry for always quoting the iPhone, but that's my reference currently and I am just waiting for the n900 to support exchange + google to be able to switch