Here’s a strange duck. Although Bose is doing this with their Companion line, these Altec Lansing speakers are USB only and include audio in and out but no optical connector. Presumably these speakers use a driver on the PC to smooth out the audio and create the surround-sound effect. It also includes a remote.
Priced at $249.95, they’re an interesting idea. Not sure how popular they’ll be.
Altec Lansing’s USB (only) 5.1 Surround Speakers [EverythingUSB]