You can only track / erase the iPad if you have MobileMe and enabled the option. If you haven't, it's not an option I'm afraid. It's good practice to have done as JustSomeJoe says and enable the screen lock and auto-erase after 10 attempts.
I hope you find it mate...can't say I'd be as sanguine about losing my iPad, but the data on it is critical. Friendly word of advice...don't keep stuff like that on file, especially if the device is portable. You should leave some things just on the RAM inside your head.