In my rant of 7 January 2003, I noted that Safari lacked deep hierarchy in its bookmarks organization. As is the case with the status bar, it's actually a non-obvious feature. When you're in the Show All Bookmarks with a bookmark playlist—for lack of a better term—click on Add a Bookmark Folder or the little plus sign at the bottom of that area. Bang, you've got a subfolder and you can keep going down. Joy returns.
Also, good review of Keynote.