What’s New:
So far as I can tell, Play is becoming a sharing and consumption hub. Instead of just being about music, Play seems to include options for books and games. Also, sharing options are likely only possible with purchased music. What I do see new with music you’ve uploaded is the ability to “Share YouTube” video. This tool checked for YouTube videos that match your song and let’s you share that on Google Plus.
It’s interesting to see what Google has planned next for these services. We’re still left without most of this in Canada. Perhaps this changes signal an impending release here?
Update: Well, it seems the entire Android Market itself will absorb Google Music and become Google Play all as one location for Books, Music, Apps, etc. Here’s what Google says about this change: