Re: Antiques Code Show
Well, the source to the original Prince of Persia was released a bit back, as was DOOM's, if I remember rightly. It does depend a lot on what you call 'significant'.
It's called Code Show in an attempt to make a pun out of the name of a certain staple of Sunday night BBC TV, namely Antiques Roadshow. Whether that's a great idea or not is questionable, but to be honest I'm not sure how much interest there would actually be in the code of old games, because an awful lot of the time it was about juggling system resources and hardware tricks that are long since obsolete.
Mind you, Quake is the rare exception in this case; there are some things about its design and implementation that are actually interesting in their own right, like the way that instead of being built in a peer to peer fashion for networking as DOOM was, it was built from the ground up to be client/server - not just for multiplayer, but single player as well. I can't remember exactly what advantages this gave, though.