-- Final Boot Camp release -- likely. (Certainly, Boot Camp will eventually be a Mac feature and not a beta tool.)

-- Built-in virtualization to run Windows without requiring a reboot -- possible, but Apple has said it doesn't plan to offer more than dual-boot options and has pushed Parallels Desktop has a solution for this.

-- Improved support for access control lists (ACL) in client and server releases -- likely, and needed. (Apple made a great first step in offering ACLs in Tiger, but these could be improved upon.)

-- Improved collaborative tools -- likely. (This speculation has been vague, but it focuses on efforts to improve the ability for users to share information from Mail, iCal, iWork and the iLife suite, as well as from Spotlight and the Finder.)

-- Improved Rosetta functionality for running non-Universal apps -- likely.