Google added ebooks to the Android Market back in February 2011 (13 months ago). So for the past year the "Android Market" has been selling ebooks which could then read on an iPod Touch. And then in May 2011, Google started selling movies in the Android Market. And this year they started selling music.
So really, Google Play isn't a bold move but a realization that Google has been a content retailer for some time now. It was past time to bring all the content together under a new brand.
I do wish they'd chosen a better name. Google Play is going to get mixed up with the search results for Google Reader Play, one of the lesser known features of Google Reader. (Guess which one ranks higher in the search results?)