Treat this with a healthy dose of scepticism, but I overheard a Microsoft rep in our local gaming emporium this lunctime - he was giving them a presentation on NXE in the shop itself.
The rep got onto BC, and mentioned a few things I've not heard before:
Apparently the full confirmed BC list is supposed to be on the Microsoft website as of today with '30-40' games at launch.
Some of the games announced earlier in the year aren't actually coming and were just 'placeholder graphics' (which I thought sounded kinda bs).
I asked the rep about Red Dead and he said 'before the end of the year'. and Reach 'dunno, probably next year'.
I do think Microsoft are playing catchup with BC at this point, even some of the shop staff hadn't heard of it, and one even said 'oh, isn't that only for the 1Tb consoles'. But they were dead excited at the prospect of possibly shifting some of the 360 second hand games.
Anyway, take it with a large dose of salt, I guess. But interesting nonetheless.