It's not as sophisticated as itunes or jriver, etc. But provides a nice straightforward interface. Appears on your TV and is easy to navigate using the remote control. Shows cover art, search by genre, favorites, etc. I haven't seen Sonos.
wireless/USB audio to receiver
If you're in the market for a receiver and/or PC-based audio, one option to consider is the new Denon receivers (4308 and 5308). I just got the 4308. It plays music files from your PC/MAC via wireless or USB. FLAC, WMA, MP3 files play wirelessly or via USB. WAV must be non-copyrighted (no ripped CDs - crazy!!). No need for cables or converters. Sure, it's no Meitner, but it's no slouch and quite nice if you're just listening to MP3s, flac, or internet radio.