Google Sync can keep your Google Calendar changes in sync with your brand-spanking-new iPad, but only through one primary calendar by default. You can switch on multiple calendars by emulating an iPhone browser and heading to Google Sync's mobile page.
Kevin Tofel outlines the process for turning on multiple calendars pushing to your iPad calendar app by using Safari's built-in user agent emulation, which effectively makes your browser pretend to be a different browser—in this case, an iPhone. You can, however, pull off the same kind of user agent switch using User Agent Switcher on Firefox or changing Chrome's user agent string, among other work-arounds. User agent switching is, in fact, how we tested out Gmail's iPad interface from a desktop browser. Once you're set up with an iPhone user agent, head to m.google.com/sync, select "iPad," and make your changes.
Hit the link for a screen-by-screen description of how to enable multiple calendar syncing on an iPad, which we imagine is a shortcoming that will be addressed very soon.