I’m not sure when the site was updated, but the EFF has dropped a Slingbox reference into their “Fair Use” manifesto. Though it doesn’t seem like HBO or others will be waiting until (if?) the “analog hole” is closed before going after Sling.
EFF says: If you can see or hear it, you can copy it, right? Not if the entertainment companies get to restrict anything that can convert “analog” sound or video to digital bits, including camcorders, sound cards, VCRs, and beyond. Congressional proposals to “plug the analog hole” would restrict both new and ordinary uses. You won’t be able to use tools like the Slingbox to send recorded TV shows to yourself over the Internet. And if you want to excerpt a DVD for a school report, too bad.