What you see here is the Kanex HDMI to Mini DisplayPort Converter that allows you the user to connect to any HDMI source device into a 27-inch iMac, LED Cinema Display, or any other Apple device.

It supports HDMI 1.3 and DisplayPort/Mini Display Port 1.1 a, and provides a maximum resolution of 1,920 x 1,200 for standard DVI, or 720p for gaming consoles.

You should be able to get it in April for $150.

Source