Thanks for the interview, Mike. This is the kind of stuff we really need to see, to boost faith that the guys in charge know what they are doing. It's about time we saw some good interviews. :-)
I'm getting into GUI design, myself, and it's nice to see that Mike knows the basics (which is all he can talk about in such a short interview). It's also important to have a GUI designer working on a project from the get-go. Asking a designer to look at your work when it is nearing completion does little to help any project, no matter how big or small. Responsiveness is probably the biggest drawback in computers these days. A bit of a buzzword, but it's nice to see that someone is taking it seriously.
My question is, are they focusing too much on the look of the OS? For what little information there is in the interview, that's what I got out of it. There's a big difference between how something looks and how it is designed. I'm personally more interested in knowing about their design rules and layout rendering engine than how many gradients you can use in the windows. The OS4 screenshots look good, but what will the tools look like? I'm still pretty ticked off at the HDToolbox screenshot I saw a year ago. I'd like to know if they are working on reorganizing and relabeling things, instead of just making things look pretty. GUI design is about placement, labels, grouping, associations, freqency... stuff that is learned through experience and talking to users (not beta testers, but sample end-users).
All I can wish for is a set of guidelines to help programmers and managers know who should do the designing. The book "GUI Bloopers" by Jeff Johnson is a good starting point. "The Humane Interface" is a bit too technical for beginners.