MacOSX with a creamy layer of IOS on top. 
Full screen apps: check
Multi-touch: check
App store: check
Apple’s 30% cut on app sales: check
Apps that auto resume: nice touch.
Well, there ya go.
I was much more interested in the netbook part of the presentation. They are still a little overpriced, but not bad considering full-sized keyboard and decent hardware specifications. I do really like that they went solid state; I wish more PC netbook manufacturers would have stuck with that instead of going for the cheaper, more fragile hard drive—it really kind of defeats the purpose of a netbook in my opinion.
As for Lion, most of the presentation was pretty boring to me. Launcher? Come on that was in OS 9 and a dozen solid third-party programs since. Not impressed. Combining Exposé and Spaces: that’s a good move. I never really ended up using either much, and it looks like they’ve sorted out all of the reasons why I drifted away from them. Exposé just became increasingly less useful as you opened more applications. Staring at a screen of tiny thumbnails doesn’t do any good—clustering an application’s windows so you can devote more space to the thumbnails is good—integrating Spaces along the top is good. I laughed at the whole “Multi-touch is the best way to interface… now just a moment… sorry about that… please wait while I try to multi-touch on my mouse and screw up the demo. Repeatedly.”
Instant-on: What does that mean? My laptop already is instant-on if I just close the lid instead of shutting down. That didn’t really make much sense to me. iPads aren’t instant on if you have to cold boot it either. Solid state does mean it will boot very quickly, at least. For true instant-on (basically never rebooting your computer) they will really need to optimise Lion to work over long periods of time. Everything at the core level will need to be as leak proof as possible. Snow Leopard is not that.
App Store: Horrible. I know some people have no problem ditching redundancy and freedom for a little convenience—but this is just awful for computing. At least it looks voluntary at the moment, but it goes against everything the market has grown out of. Small developers are going to have to charge 30% more for their software if they want to fit in with the crowd and still break even. If they don’t use the App Store, will they get muscled out of the game because the average user never checks MacUpdate any more?
Well, at least it wasn’t iOS is coming to the Mac. There is that—and for about five minutes in the presentation it was scary like that.
Speaking of scary: Steve Jobs looks about ready to star in a Hollywood remake of The Machinist. Is he still drinking herbal tea to cure his illness?
Oh, apparently Scrivener was one of the applications in the keynote, during the launcher demo. Anyone else catch that? 
How will Scrivener 2 work on a small 11 inch display? Or is 13 the smallest recommended size?
-Chad
Engadget caught it:
Actually, in this case, because these screens have such a high resolution, it shouldn’t make too big of a difference. Higher resolution means text is legible at a smaller size, and the “bulk” of the application’s control areas can be more easily represented in a smaller space as well. The 11" is about the same size as the current 13" MacBook, and the 13" Air is about the same size as a 15" current MacBook Pro.
I know they said they are on sale now, does anyone know if they are actually in Apple Stores yet?
Update: Looks like they are. Here is one shot from the Engadget crew in what appears to be an Apple Store:
Looks like a 15" MBP that it’s sitting on, judging by the speaker you can see on the left.
I heartily recommend the Air for writing on the move. It’s so small and light that you can use it in the most cramped situations. When at home I can sync music, films and other content with my Mac Pro so I always have new content to entertain me when away.
I’ve had mine since they came out and wouldn’t part with it for anything. I’ve got more work done on it (by which I mean both writing and day-job work) than I ever did with my company-issued Thinkpads. It’s because of my Air that I was never tempted by the iPad. Not even a little bit. I even use it as a streaming video client to watch films on my TV using the shared iTunes library from upstairs.
Totally smitten. We are rarely apart. Boots in 20 seconds, shuts down in 5.
Eddy
… the Inventor of Fullscreen Mode (again) 
Apart from that, I suspect a bit they might want to copy their WeHaveToCertifieSoftware (aka App Store only) principle of the iPad to the Desktop version of OS X …
Time for Scrivener to head for a Linux variant?
The App Store is a great way for Adobe to gain tons of new customers … when selling the Creative Suite for a typical App Store price like $ 7,99.
But seriously: As far as I know the present App Store guidelines do not allow upgrades of any sorts. How should that work with applications that cost more than just a few bucks?
The most scary moment of the keynote for me was was when Jobs started with multitouch in OS 10.7. It did not yet relieve me when he said that multitouch doesn’t go with vertical displays because I had this terribly Apple patent in mind which shows kind of a fold-in iMac. But then: Multitouch with pads. Phew.
I would like to thank you heartily for this question because, even though - as Ioa points out - Scrivener is built to run on resolutions of 1024x768 and will therefore certainly be fine on these new MBAs, your question has provided me with the justification I need to order myself a nice new 11" MacBook Air. 
Great! So, you will test Scrivener on it, before I receive mine!
Paolo
Scroll down if you wanna watch Engadget’s hands-on video: engadget.com/2010/10/20/macb … -hands-on/
The 11.6-inch MacBook Air looks so…tiny!
This is an interesting take on the coming Mac App Store, from a developer I respect quite a bit.
Creepy things, those three-finger mouse gestures.
Still trying to remember if - apart from the new mba - there was anything really worth remembering. Fullscreen is nice for single-monitor computers and mostly useless on multiple monitor setups.
Some of the ideas for the new iMovie are nice, agreed. I still wait for any decent and easy audio editing in Final Cut Pro apart from “oh, just send it to Soundtrack Pro”.
The autosave - Keith, you should have patented it for yourself - will hopefully transcend into all applications. Even the resume. However, it is not an function provided by Apple, but - like on iOS - has to be provided by the developer. To “provide” this, all Apple will have to do is making it a part of the new Mac App Store guide lines and they are finished. Funny.
I might be blind or preoccupied - but I did not see anything truly remarkable.
Hardly anything useful, for that matter.
I agree that what you’re seeing is nothing remarkable, but what Apple is doing is laying the groundwork for their vision of computing five years from now. Lion is just the stepping stone.