My ISP has a service that for 3€ a month you can stream any music to any device, smartphone, pc, tv, tablets etc. any music from their catalogue that has millions of titles. for 5€ you can stream TV too.
This mSpot sounds stupid. Anyway can make a simple server for streaming from pc. Actually there's even free servers that allow that.
I have 25Gb of free storage on skydrive, roughly 7000 mp3s that i can stream to a music app on WP7, or indeed any nunber of any devices anywhere, all for free.