After we linked to instructions for how to burn a Lion boot disc earlier this week, Nature's Eye Studios contacted MacStories to let them know they figured out how to get the new OS to boot off a SD card. After downloading Lion from the developer site, the video maker proceeds to wipe a SD card and use the repair option with the Lion disk image as the source to create the boot. Once you've created the backup, you can use the SD card as a Lion installer if needed, then pull a backup from Time Capsule.
Keep in mind that the final release of Lion will include a restore partition and Recovery Mode, meaning that you'll be able to boot your machine from a clean Lion installer at any point without the use of external media (assuming your hard drive's not wonky). While this means you're a lot less likely to need install media down the road, it's nice to know the option is there.
Check out the video below to see this process in action.
Apple OS X Yosemite