Now that the demand has settled down, the mobile me push services are up and running.
Emails show up on the phone instantly. If you change contacts on the Mac, then sync, they show up on the phone. Same for Calendars.
To enable this, you need a mobile me account. Then go into your email settings, tap mobile me, then slide on both contacts and calendars.
Make sure you have synced with mobile me before you do this, just so you have data to pull down.
Once you do this, contacts and calendars will no longer sync via iTunes – they will be handled by mobile me.