@attila: very interesting. I read somewhere that high-def movies from itunes store come in multiple resolution for the different target device (desktop & apple tv + handheld version), and you're right, this could be making use of that feature of the stream is indeed embedded in the same file.

But 'transcode' may not be the proper term.. just multiple streams with different resolution & bitrate in a single container.

Other than Archos (which I heard is a licensing nightmare, having to buy codec plugins and all that), you can check out the Creative Zii too...