OS X Lion: About Lion Recovery Disk Assistant

The Lion Recovery Disk Assistant lets you create Lion Recovery on an external drive that has all of the same capabilities as the built-in Lion Recovery: reinstall Lion, repair the disk using Disk Utility, restore from a Time Machine backup, or browse the web with Safari. This drive can be used in the event you cannot start your computer with the built-in Recovery HD, or you have replaced the hard drive with a new one that does not have Mac OS X installed.