HardwareSecrets will tell you everything you need to know about HDMI; especially useful if you're in the market for a new HDTV.

"The idea is to use a single cable instead of several cables when connecting your DVD player to your TV set, for example. This new connection standard was developed by Hitachi, Matsushita (Panasonic/National/Technics), Philips, Silicon Image, Sony, Thomson (RCA) and Toshiba."