I recently downloaded DEFCON, from the makers of Darwinia.  I haven't had the chance to play it yet, though I hear it's fantastic (too many good games and I don't want to give it short shrift).  What is quite interesting to me is how much buzz I'm hearing about it through friends, message boards, email, etc. for a game that has no physical presence at all. 

I know that's not a first for Introversion, at least at the start, but it is really showing me that the age of digital distribution really is starting to dawn upon us.  Good times.