If Lion was preinstalled on your MBP then you have a recovery partition. Press Command + R as soon as you hear the POST chime (bong) and the machine will boot to the recovery partition where you can use Disk Utility to do general maintenance such as repairing permissions and verifying the hard drive.

You can also completely erase your hard drive and reinstall Lion from the recovery partition.

If your hard drive should crash so that it is inaccessible, the recovery disk you made can be used in lieu of the recovery partition.