At this time there is no direct method from within PocketRSS to backup your data. However, you can use File Explorer to accomplish this task. Simply navigate to the install location of PocketRSS (Program Files\HappyJackRoad\PocketRSS) and copy the "cache" sub folder and the "scripts" sub folder to a safe location.

If you have to do an install on a new PocketPC, you can simply copy the backup "cache" folder over the existing cache/scripts folder and you will now have available all of your previous PocketRSS sources.