Sorry, here it is: It says "please don't quote me", that's why I just wanted to post a link first. But I guess there shouldn't be a problem copying it here.
Enjoy:
I found these posts on a thread, guy claimed this "Disclosure Agreement (NDA) with Apple precludes me from revealing proprietary detail, but because most, if not all, of this is posted elsewhere and is commonly available, I have no problems with confirming the following. Still, please dont quote me."
1. Leopard supports OS 9.x, as is done with Tiger, but OS 8 and earlier will not be officially supported. Legacy apps may still work, but Apple just wont support them.
2. During the Leopard install, you are given the option to create specific partitioning to accommodate M$ Vista and Linux. Reformatting your HD is not required. Depending on your processor and RAM, all OSs can run simultaneously & independently. A (minimum) 150 GB HD is required (250 GB is recommended), and 2 GB RAM (minimum) should you wish to run more than one OS. Dual processors are required for optimum performance, though this may change in 10.5.1 or 10.5.2.
3. DiskWarrior (in lieu of TechTool) will be bundled with 10.5 if one chooses Apple Care or extends their current Apple Care contract. I dont know the pricing or specific details, though Apple Care for older machines will increase significantly with the machines age. Machines over 6 years old (from date of mfgr.) are not eligible.
4. Safari will include editable Helpers. Safari Tabs can be assigned colors. Safari will be about 37% faster (YMMV). The default for Safari bookmarks will now be alphabetical by folder. Safari will include configurable parental controls (for those who want configured parents). Safari will now import Firefox and Camino bookmarks. Also, there are 12 new Safari skins.
5. The Dock will be much different. One new feature is that as icons are added, they will automatically migrate/expand around the screen as needed (or, you can reduce the size of the icons as presently done). Also, multiple docks are an option as is the amount of bounce desired in those dock apps launching or needing your attention. There is an accompanying bounce sound, a boing-boing sort of thing.
6. Hooks are built-in to support an Apple PDA, but I can say no more.
7. All Metadata will be editable.
8. You can have 3 Finder windows open simultaneously, much like having 3 displays, all running different applications or OSs. If networked, any 3 computers can be displayed. Depending on the function/application, you can even Drag & Drop between displays. Password or Admin. privileges are required. (see #2 above).
9. Widgets can run on any or all of your open windows, similar to the way Stickies can be placed anywhere.
10. Terminal has balloons that will appear with alerts/warning notes should you wish to do something that you will (later) wish you hadnt.
11. Mail, Address Book, iCal, iSight, and iChat will become one integrated application, much like Entourage (but better). Included is a customizable Auto Responder and voice activated dialing via numbers or Address Book names. You will be able to automatically send email & initiate iSight meetings, etc. that are linked/pegged to specific calendar events. This feature is called AutoPilot (see #6 above).
12. Voice recognition/security has returned as an option (see #6 above). Note: Use with caution. I am still not certain this will make the final release (its still a bit buggy); perhaps delayed until 10.5.1.
13. An across the board speed increase of 35 - 40%. YMMV.
14. Font, Printer, and User Preference (.plist) repair routines are built-in and are schedulable.
15. Sherlock has been eliminated (use Widgets instead).
16. When Repairing Permissions, the We are using special permissions
will no longer be displayed. Finally!
17. Airport (Extreme only) will notify you via the airport icon flashing in the menu bar if your signal is being hijacked or used by anyone other than you authorized.
18. Startups, Restarts, & User Switching will be exactly as the User left the machine; open apps, window positions, network connections, etc. will all be reestablished.
19. Bundled with Leopard is a small app called TrashBack, a program to recover deleted files. Of course, the sooner one uses it after trashing the better.
20. Numerous (other) bug fixes, including a totally rewritten Spotlight.