Here it is - Google Classroom. I'll leave it to others to analyze what these means, but comment on just one line in the announcement:
Like the rest of our Google Apps for Education services, Classroom contains no ads, never uses your content or student data for advertising purposes, and is free for schools.OK, so Google will not use your content or student data for ADVERTISING PURPOSES. That leaves out a world of other possibilities.
So bring it on Google! It's gonna be fun.