What the little demo didn't show is what exactly happens with that file he downloaded. Is it accessible in the Finder to be "kept forever" or has the computer truly become just another iOS-style "device" where the underlying file system is not really accessible, and the downloaded track is only visible or able to manipulated from
within iTunes? Is the iTunes Library now like the iPhoto Library?
Personally I don't care, but there were some
heated arguments a while back about whether iTunes Match would be purely streaming or would actually let customers "keep" all the 256kbps files they could possibly download/hoard, essentially making it an all-you-can-eat buffet for a one-time $25 fee. Looks like the streaming is clearly in place, but whether or not downloading means "for keeps" remains to be seen. My prediction: no.
Also curious if the latest iTunes will close the CD-burning loophole. Apple's deal with the record companies on this is suddenly believable if all the tracks are "trapped" inside of iTunes on the various devices, including computers.