gizmodo points out that the new portable media center edition have shown up on amazon for pre-order.
i ran mce on a desktop at work until i tried to update to a beta, two weeks ago and ran into a 48-bit LBA problem on the 160G drives that i've got in there. i liked the UI and prefered some bits to tivo. i won't give a full review of the old one, as that's been done by others. after i get the beta working with multiple tuners and the rest of the features, i'll post something.
i'll wait until i have a chance to play with the portable version before i render a verdict, but some of the teaser videos i've seen are pretty compelling.