I had the same question. Here's the answer from the Apple iPad microsite:
Everything comes together.
You have an iPad, a computer, and an iPhone or iPod touch. How do you keep all your calendars straight? It’s easy in iTunes. Connect your iPad, iPhone, or iPod touch to your computer, and iTunes can sync every meeting, event, birthday, appointment, and reminder in every calendar application you use: iCal, MobileMe, Google, Microsoft Outlook, AOL, and more. MobileMe syncs everything, too — and it all happens wirelessly and automatically.*
Next I'm searching to see how it handles email. I'd love it to sync between iPad and my iMac, unlike the lack of sync between iPhone and iMac.