The Panther Finder is brand-new, with a new brushed metal appearance, and enhanced column view, with the items used most commonly in the far left column. Searching is "live" and a lot faster, and is more user-centric instead of computer-centric.
The Finder now has labels, and icons can resize with window resizing.
The iDisk now caches itself locally, so it can be used offline, and the user can copy to and from it more efficiently (with the real copies happening in the background).
A new feature called Expose allows minimizing into a smaller window, all open windows, to temporarily move everything out of the way, sort of like workspaces.
File Vault can encrypt a user directory and decrypt it "on the fly."
Faxing is now built-in, and available system-wide.
Pixlet is a new compression codec that does video compression without noticable artifacts, for 48 bits per pixel: at 960x540 and 24 fps, can be decoded on a 1GHz Power Mac.
Preview is significantly faster, with searching, and PS to PDF conversion.
Panther features fast user switching, a feature in Windows XP, allowing under-one-second (on the demo machine) switching between two different users.
FontBook is a new "pro" app for font management.
iChat AV is an update to iChat that does audio and video conferencing in addition to text, that works with any built-in or USB mic, and any DV video camera, connecting using only a user's screen name. It is going to beta today, and will be included in Panther, and will be sold for $29 to Jaguar users. Apple will sell iSight for $149, a small camera that does audio and video over FireWire.
Apple is preparing a new set of developer tools called XCode, which works with GCC 3.3, does distributed compiles (using available resources on the network), and has other cool stuff. It is fast, it has improved searching (like the Finder, and over entire projects), and it looks like an iApp (though it isn't metal). It removes the need to link; onnly link objects you need to launch. It starts compiling while you are editing, cutting the time you need to compile drastically. It can modify the program while it is running.