Here's the full announcement:
Exciting news today — we’re thrilled to welcome +Songza to Google. They’ve built a great service which uses contextual expert-curated playlists to give you the right music at the right time. We aren't planning any immediate changes to Songza, so it will continue to work like usual for existing users. Over the coming months, we’ll explore ways to bring what you love about Songza to Google Play Music. We'll also look for opportunities to bring their great work to the music experience on YouTube and other Google products. In the meantime, check out their service on #Android (http://goo.gl/urYGx6) or iOS (http://goo.gl/c0egja) to find a playlist for any mood you’re in — whether you’re feeling a little mellow or a lot funky.
You can download Songza from the App Store for free.