How to play hyperlink to mp3 on Android
I use MixZing music player. I have set it as default player for music and when I click a mp3 file link in browser, it opens the file in MixZing by default and streaming works well. It plays the mp3 file in background when you press the back button.

This is an alternate solution. I don't thing it is possible to play the mp3 links in background in Android's default music player.