AppleTV has a good shot at making the living room more fun. The price is reasonable, but more importantly, the usability is extremely high. The only way Microsoft can "win" against AppleTV is to "win" in an Xbox fashion: loose huge amounts of money for many years. I suspect they may be willing to do that, but it will just be embarrassing.
OS X 10.5 ("Leopard", but I'm getting sick of the cat names since I can't keep them straight) will be worth the expected $130 upgrade cost. I'm surprised to be saying this because I normally grumble at the cost. The demo in the Apple booth showed why Apple is Apple and Microsoft isn't. It's not just about new features: the user interface for them is flawless. Time Machine is amazingly good, and I hope that the developers of all my other apps integrate with it. The Spaces interface may be the first workspace app that is understandable by typical users (not just the dweebs). And the screen sharing / help feature in iChat is also excellent (although I expect Apple to badly muff some of the implementation like they do with every version of iChat and Mail). All in all: it looks great.
The iPhone (and I really do hope it will be called "iPhone"; Cisco is just being greedy here) will be very popular even among non-Mac folks. Many people said "Palm is dead", including two people using recently-bought Palm devices, and one person who recently worked at Palm. "There is no reason for them to exist any more." When the iPod came out, there was a general feeling of "this is an MP3 player that has the elegance and feature set of a Mac"; the iPhone has that exact feeling. Two people noted important missing capabilities: 3G networking and GPS. I suspect those will show up at the release or in the first feature bump.
VMware is about to blow it with their competitor to Parallels. Fusion is extremely late, the first beta is very buggy, it is expected to cost as much as Parallels, and it will not have any significant features that Parallels doesn't already have today. As a long-time VMware fanboy, I'm really disappointed.
I saw exactly two people carrying iPod Shuffles, as compared to hundreds carrying iPods with screens. I have no idea why this is.
Without the iPod skins booths and the iPod speaker dock booths, Macworld Expo would be at least one third smaller. That's scary.
SATA just works. That's good to know.