https://play.google.com/apps/testing/com.ntrack.songtree
They also have a page dedicated to some of the collaborations. Do think that this can be a major outlet for people that play real instruments as is heard on some of the tracks that are highlighted. It can also become a excellent way to find musicians or to take basic recordings of your own to let them grow into full songs and lead into unexpected places.
Was a little bit dismissive when reading about Songtree at first but having heard some of the high lights and seeing it for more of a outlet for real instrumentation and not electronic meanderings that go nowhere, I now see the possibilities.
Now just need to send some acoustic guitar tracks into the Songtree eco system and see what happens!
To hear the highlights and grok the full impact that is the idea of Songtree go here:
http://songtr.ee/highlights