Pretty hyped for this, I saw the MS E3 gig and it was a pleasant surprise.
Question: will this apply to Arcade games on your account, or just retail games? I'm not too bothered about retail games (though it'd be nice, obviously) but I have a number of arcade games (DN3D, DOOM, TWD, etc.) on my 360 that I rarely play now, but I would play on the XB1 if I could.
For me, that would be awesome.
They will constantly update the catalog, so if your arcade game is on the list, it shows up on your Ready to Install section on X1.