Why aren't there any cooled CCD sensors to reduce noise?

Sensor cooling is a common technology to get less noise. Why isn't it available on high-end D-SLRs ?

(see http://www.andor.com/scientific_cameras/ikon-m_cooled_ccd/ for an extreme example)

I'm not saying D-SLRs should be cooled with liquid nitrogen. Just some cooling system !