Seems like Google accidentally released a developer build of their latest Music Player app update, which offers some strong indicators the much rumoured cloud music service is coming soon.
Tech from 10 is hosting downloads of the app here (the site is currently down, but Engadget says that Droid Life is also hosting the app) and Business Insider says the app has a currently non-functioning option to connect to the forthcoming Google music service. [Tech from 10 via Business Insider via Engadget]