There is good news and bad news with the release date of this highly anticipated FPS, bad news release is scheduled for 2007 good news is that inevitably the price of the X Box 360 will drop after Christmas, Also there was news this week that the PS3s release date has been set back again and the possibility that the Blu ray technology might be removed which will take away the sony consoles multimedia advantage.
There is a detailed article on halo 3 on the Bungie web page, take a look at the trailer video real eye candy 
