Internet "sharing"
1. Through the USB cable: you can download PDAnet. Then you can tether to your computer. (only works for windurrs)
2. Ad-hoc wifi sharing. Requires you to have a rooted phone, there is software available to turn your G1 into a wireless AP.
Activesync:
Is software used by windurrs based phones and PDAs. I suppose you could hack something together to get it to work with a G1, but it's fairly pointless, in my opinion at least.
edit: Ah snap, just read the "Magic" portion. I suppose you can use some of this information.
