A few things people seem to be glossing over and/or weren't covered directly in the keynote, itself:

1. Spotlight now supports a more reasonable, powerful query language (AND, OR, NOT, explicit associativity, date:/format:/etc.) It's really, really sad that I've historically found it easier to find email by cmd-tabbing to a browser and running a search shortcut against my Gmail archive than searching directly in Spotlight or Mail.

2. ObjectiveC 2.0 Garbage Collection, significant runtime improvements, and new syntactic sugar to reduce verbosity. This is huge, the average user just won't realize it for a while until the average app starts getting faster, leaner, more stable, and more rapidly-evolving.

3. DTrace for OS X

4. Xcode 3.0 [http://www.apple.com/macosx/leopard/xcode.html] Among other things, the debugging and profiling tools (using DTrace -- #3), look dramatically improved.

Now I just hope Time Machine is as powerful as I first imagined when reading the real-time news feeds (real-time snapshotting in the filesystem, with lazy mirroring of the version tree to external and/or networked volumes), and not some lame batch process as I now fear. This could be either so good or so non-functional, depending where they've gone in the implementation.