iLife and iWork both ship tomorrow, but a number of people already have their boxed copies, so I figure it's OK to run this hint (and the iPhoto hint a bit further down the page) today, as the programs are out there...
The new version of Keynote adds 10 new themes, all of them very nicely designed. However, probably in the interest of symmetry (20 total themes), two themes have been left behind -- Sandstone and Leather Book didn't make the cut, it seems.
If you have the first version of Keynote, however, it's easy to install these themes for use in the new version. First, make sure neither version of Keynote is running. In the Finder, control-click on the Keynote application and choose Show Package Contents. In the new window that opens, navigate to Contents -> Resources -> Themes. Now open a new Finder window and navigate to the top-level Library -> Application Support -> Keynote -> Themes folder (create the Themes folder if it doesn't exist).
In the first Finder window, hold the Command key and click on each of the following files to select them all:
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050121073354254