Christina Warren for Mashable:

Because installation takes place entirely from within the Mac App Store, the usual “clean install” option isn’t present. If you’ve followed our guide for preparing your Mac for Lion, you’re probably in good shape to proceed with an upgrade. If, however, you long for the ability to do a clean install without having to first install Snow Leopard and THEN install Lion, Mashable has you covered.

Christina takes you through the simple steps to create the disk. Great if you want to have the clean install option at some point.