Now that you have a Quicksilver cheatsheet and manual, check out one of the most beautiful UI plugins I've seen for this app: the Cube Interface. Tim Gaden at Hawk Wings has put together a short video of the interface in action, catching the drool-inducing eye candy in all its glory.
I'm not sure if this interface is only available to the Quicksilver developer build versions or not, as I am running the same version he is. If this is the case and you're still eager to take the plunge though, you can enable and access this version from Quicksilver's Application preference tab. However, if you're just getting used to this app or prefer stability over new features and eye candy like this, I'd recommend waiting until the Quicksilver crew brings this more mainstream.
The Google Maps Plugin for Address Book has updated to version 2.5, adding Universal Binary super-powers and a slick new feature: Google Earth support (which is handy, since 
Macworld is 
I need to make more of a habit of rooting around in Quicksilver's plugin pane, as I almost always find stellar new tools each and every time I open it. This time around I stumbled on a Yojimbo plugin for Quicksilver that seems to do a better job of adding items to the Yojimbo database than the bookmarklets that BareBones added themselves in the latest 
