Having written this kind of stuff myself for various platforms, I can tell you..
1) QuickView is not revolutionary, but it's not trivial either. Those things opened up instantaneously. Granted it might not be as quick on machines with more reasonable amounts of memory (that demo machine had at least 4GB of memory of the 32/64 bit test would have been a waste of time.) It's a pluggable framework and it is the underpinnings of iChat theater. It's a lot of work to implement well.
2) iChat. Apart from UI updates (FINALLY tabbed chats! I suspect most of the work in here is around iChat Theater, building on QuickView, and fancy stuff like effects etc. Not groundbreaking, but a decent step up, and don't forget, the fun stuff is why average consumers (and lets not pretend ANY of us that frequent these forums is a good representative of one of those!) like macs. Of course there's stuff in there for that. He's targetting a market. He's VERY good at that you know.
3) Screen sharing, while not demoed, and not obvious in iChat, is building on Remote Desktop, but making it more integrated. It's a neat touch. It makes things easier. It's worthwhile.
4) New Desktop/Finder/Dock. How on earth can anyone on these forums have the first clue how hard / big that was to develop? It's not trivial just because it doesn't jump up and bite you with its "newness." The way the Finder, the desktop and the dock interact in OS X has been a collosal hack for a long time. If they've cleaned that up and made it easier to make them play nice with one another then it's a big thing. How often have you had the Dock ignore you coz Finder was busy deciding a network share had gone away? Annoying isn't it. Posts in other forums suggest responsiveness (the most meaningful performance measure for a UI) is way up in Finder. The fancy glass effects, well OK not the most important thing in the world. Odds are you can turn it off in any case if you hate it so much.
5) 64 Bit. This is huge. Mammoth. It's an absolutely massive task to make an entire OS 64 bit and still able to run 32 bit apps along side, and have one code base which supports 32 bit CPUs as well. Microsoft have how many developers? That didn't do it with Vista. You should give them credit for this. It's not immediately earth shattering, but then 16bit to 32bit was fairly meaningless to the average consumer when that happened too. After a while when people learn how to take advantage of it, big things can happen.
People have said that Leopard is small, it's not got a lot of big things in it like Tiger. But you are missing the point. An OS X release is two things. 1) The operating system and 2) A big bunch of Apple apps that come with it. They've done a TON of stuff on the OS side of things in Leopard. And they've actually made a lot of refinements in the apps side.
What I don't get is that people want something BIG from Leopard, but think about it for a moment. What Apple excels at is attention to detail. That's why you like your mac so much more than a windows machine. Because things work the way you would expect them to, not the way some software engineer happened to code them. A lot of little tweaks, refinements and enhancements can add up to a whole lot of "better" at the end of the day.
I agree, the actual Keynote was not up to usual standards (hey, at least he didn't have half of apple come up for 5 minutes at a time to talk about things like last year!) But Leopard, there I'm holding my judgement until they deliver it. I am optimistic. I think they've done a lot and I'm not going to pre-judge something I haven't even played around with yet.
be well
t