There's a lot of things they don't mention.
For one thing, almost everything they list for Longhorn is already in Tiger or even in Panther (which is already released).
For example:
The biggest visual changes will be seen if you have a reasonably speedy 3D graphics card. According to PC Magazine's Code Name: Longhorn A New Look, if you've got the power, then Aero Glass will employ 3D effects, transparency and animation. If not, then a basic version of the new interface that doesn't require 3D power will be deployed.
This is already implemented in Panther, with animation and transparencies and effects, though not to a great level (no 3d effects like lens rays or glows or anything, just moving the windows around rapidly and stuff like that), in the form of Quartz Extreme. Tiger will take it to a new level with CoreImage and CoreVideo, allowing for real-time 3d effects on anything.
So Tiger has that, as well, and Panther even has a form of it.
Along with the new look, the new interface will include support for music files and digital photos, such as the ability to create slide shows or run a simple image editor that's built right in.
Supported in nearly every version of iPhoto since 2003, Mac users can create slideshows in two seconds with 3d transitions (page wipes, Cube transitions where each photo is one side of a cube which rotates, etc) and music playing in the backgrounds.
I hate how they downplayed Mac OS X's security to make it sound like its just because of the lower market share- that is not the case.
http://www.baltimoresun.com/technology/custom/pluggedin/bal-mac082803,0,1353478.column
They also never mentioned when Tiger will be released (summer this year). By the time we get Longhorn we'll probably get Mac OS X 10.6, which will be even better than Tiger!
Also,
Indigo, to oversimplify, promises to make it easier to integrate desktop applications with web functionality.
I don't know if OS X has given it a name, but I believe it already has it. After all, 90% of the Dashboard widgets have web functionality, Sherlock has integration with web functionality (address book, flights, dictionary, etc).