Spotlight pop-up effects I saw someone with a Macbook Pro using the Spotlight feature several times, and every time the Spotlight opened, it used a certain effect that's not like what I see in other Macs (I use Leopard). 

The effect I'm talking about is like a vanishing "teleport" effect, it opens up starting with a thin, long horizontal bright line which shortens and expands in height until it reveals the Spotlight. To see a similar effect, use a recent version of Safari with several tabs open, and drag one of the tabs down as if you're going to break it off into a new window.

Does this effect happen to be OS based, or exist from a third-party tool (Something like Compiz, but for Mac)?
It sounds to me like you may be describing Quicksilver, which is, among other things, an application launcher.

http://qsapp.com/index.php

I use it daily and it can look very much the way you have just described.  It has several different interfaces.

However...  It is definitely not spotlight, and it doesn't use any spotlight like icon...   

Mine also pops up in the middle of the screen, not the top right like spotlight....

Does this sound like what you may have been looking at?