Apple’s new OS X Lion Developer Preview apparently changes the way that users can reinstall their computer or restore from a Time Machine Backup. According to CultofMac, Apple has now added a recovery partition to OS X. The recovery partition basically acts as a stand-in for your 10.7 DVD or your computers restore DVD, and contains all of the options that are contained on the original installation medium.
While some computer manufacturers, such as HP, have done this with Windows computers (requiring some configuring and work by the OEM), it appears the feature has now become a standard, automatic feature of OS X Lion. I suspect this is just another was for Apple to help their users overcome their dependance on the optical drive, and may in fact be a preparatory step for removing the optical drive from future Macs.
Check out the details, as well as an image gallery, over at CultofMac.