Update: It's been confirmed that PlayStation TV will launch in the UK this Autumn for £89.99 and will not come with a Dualshock 3 controller, however it does work with this controller and the Dualshock 4, so if you are using it for streaming purposes then you likely have a controller anyway.
The device will be compatible with PlayStation Now, allowing you to stream PS3 games instantly. It'll also allow you to play select PS Vita titles and stream PS4 games to another TV. Other services, such as video streaming and the like will also be available.
Original: Sony have announced the previously announced Playstation TV, which was originally only available in Japan under the name Vita TV, will be available in USA, Canada and Europe this Autumn.
The unit will be available for $99 in the US, no word on UK pricing yet.
A bundle will be available $139 including the PS TV unit, DualShock3, Memory card and Lego The Movie VideoGame.