What you WILL see in Jaguar (10.2) -- some of this is already well known:

* spring loaded folders.
* Finder labels just like OS 9.
* improved contextual menus, but still not customisable.
* better threaded Finder (eg connecting to servers).
* CUPS support -- it IS in the internal builds, just not the seeded ones.
* SMB browsing -- once again, it IS in the internal builds.
* 15% speed boost all around from compilation with PPC-optimised GCC 3.1 (this will apply to the
OS itself and all Apple-vended apps. Other developers will have to recompile.
* Ability to turn off anti-aliasing via the System Prefs (one less use for Tinker Tool, I guess).
* Improved Mail.app with more filtering options and SpamCop (spam reporting) integration. GPG
support and integration now standard but GPG will NOT be distributed with the OS due to GPL
licensing issues, so users will have to DL and install a separate pkg.

What you will NOT see in Jaguar but is currently in very early builds of Leopard (10.5):

* Carbon Finder (still). You are NEVER going to see a Cocoa Finder.
* Ability to define unlimited additional Finder labels (ties in with DB filesystem featuers -- more on this below).
* Split dock feature. It's almost like multiple docks, but you can only split the dock into segments, and those
segments still remain on the same side of the screen.
* iTunes-style searching of the file system using a "browse" mode. Searching is done based on file-metadata
stored in an extended HFS+ spec (backwards compatible, more on this later) in an effort to copy and improve
upon the DB-like aspects of the BeOS filesystem.
* Much work is being done on getting a "switch user" feature going like in WindowsXP, but still only in preliminar
y stages. We can hope...
* New GUI element for browsing file system: the "pile". This extends the file/folder metaphor by allowing the user
to group documents in piles which are represented on screen as a stack of docs, each one slightly rotated so you
can see the edges of the one underneath it. Anti-aliased Quartz proving really handy for this.
* Support for future Apple hardware: eg. 64-bit from the ground up (read: G5), USB2 support, Firewire2, faster Airport etc.
* HFS+ to support softupdates (similar to FreeBSD softupdates) which provide journalling filesystem like capabilities
(ie. quick crash recovery) without actually being a journalling filesystem. These extensions are backwards compatibile
with today's HFS+ in the same way that ext2/ext3 are interchangeable on Linux.
* Much, much more.

The ONLY people who are being seeded with Jaguar builds at the moment are Apple's biggest and best buddies
(eg. Adobe, MS, Macromedia etc). Clearly, NOBODY outside of Apple has seen Leopard yet. That info comes from
my friend who works at Apple (an HI guy). Expect to be waiting a long time for Leopard though: MWNY 2003 at the earliest.