I agree with most comments. "Play" sounds like something I'd expect on PSN or XBox Live. I don't play a utility or book, nor would I buy a book (or video) from Google. I go to that store for apps and nothing else. Prices are pretty much cheaper on Amazon for music, books, etc.
Companies are listening to marketing "professionals" and making moves which don't seem to work well with the public. Calling it "Play" makes it harder to discuss. Which makes more sense:
1) Just go over to Play and search on "Juice Defender".
2) Just go over to the Market and search on "Juice Defender".
For me, #2 makes more sense.
Apple calls their latest iPad, "the new iPad", which will only make sense for a short while. If you buy one today, how will you refer to it in 2 years? Users will call it the iPad 3 whether Apple likes it or not. I think Amazon did something like that with the Kindle 3 which is (I believe) officially the "Kindle Keyboard".
In effort to distinguish themselves companies are naming things in ways which make little sense for the common person.