First of all, I want to make it quite clear that Spotlight needs to re-index your entire internal/ boot hard drive when Leopard boots for the first time. This will require that you’re in an administrative user account.
Secondly, Spotlight in Leopard is a handy calculator and dictionary. Any type of basic math (+ - / *) is useable in the Spotlight menu. So, for example, if you typed “2+2” then before Spotlight returns any other results it will show you the answer (4) as the option of the Calculator application. Same for single words, before the rest of the results pop up Spotlight will return the word as a link to the Dictionary application with the definition there.
Spotlight now has support for boolean logic. You can add commands like “AND”, “NOT”, or “OR” into a search query and it will use that to form the results you get.
Also, showing all results from the Spotlight menu now opens a Finder window with those results.
The Spotlight menu icon is now quite a bit more integrated-feeling because it is black, just like all the other menu items.