It is, and that's exactly what I used to do with a Linux box running as a dedicated jukebox for both my home stereo and for internet streaming. It was terrific.
Yes, that is quite a compelling feature, but I feel like there's nothing revolutionary about it. The non-technically-inclined have been using Grooveshark for a few years to do that, and nerds can just run their own streaming mp3 servers. I'm just a bit disappointed that there isn't any nice functionality like I mentioned above - this seems like just another cloud storage service with a decent and simple Flash interface on top.
And I can't see why Google didn't go farther. Whatever Apple's rebranded MobileMe turns out to be, it's almost certainly going to be more ambitious than Google and Amazon's services. Google has to know that. I just don't see why they didn't really act on it.
Now I just need my phone to auto-realize it's in the car and start playing music over Bluetooth or something to the car stereo. Too bad I have an iPhone - if I had an Android I'd be tempted to implement this myself.
Has Android and iOS clients, and is also accessible via the web. It's not as clean and polished as I'd like, but it works reliably enough for my tastes and is fully open sourced.
That isn't compelling?