You can get Now TV on mobile devices (iOS and Android), online through the Now TV website. To get Now TV on your TV you could use a PS3 or Xbox 360 and now the new Now TV Box.
The Now TV Box is remarkably small, less than 9cm wide. This form factor is very similar to the Apple TV. It's also very cheap, only £9.99 to purchase, including postage and packaging. The device includes access to a small range of other services including BBC iPlayer, Spotify and Demand 5.
Disappointingly for a new device, a likely a result of the low cost of the box the HDMI output is limited to 720p resolution.
For more details check out Now TV's webiste: https://shop.nowtv.com/