I've been trying to use Spotlight as my primary app launcher (after being a diehard user of Launchbar and then QuickSilver). One thing that annoyed me about Spotlight is that you have to enter your query, then cursor down to the "Top Hit" before hitting RETURN to launch it.
I just stumbled across this... If you enter your query, and after there are some results, just hold down the COMMAND key and the selection will toggle between "Show All" and "Top Hit" - so a quick "Command+Return" will launch the top hit quickly. This is likely documented somewhere, but I can't remember the last time I RTFM for MacOSX... Ever?
Spotlight still sucks at acronym handling (like being able to enter "shpp" and have it figure out that I mean "Sharing Preference Pane" rather than having to type "Sharing P" before it triggers). Both Launchbar and QuickSilver handle acronyms amazingly well.