@temporance:
It won't be a copy, I remember Ivan's early efforts with MPEG-4 video and it was quite impressive for back then (think it was back in the DivX 4 era, I've got the demo encoder somewhere, ill dig it out)...and completely different to any other encoder.
(Although I have a (cynical) feeling this won't be mind blowing quality...first releases rarely are. But I'm sure they'll keep update it often)
as for mp4, im sure it won't be a problem to take the mp4 and put it into mkv.
-Nic