Gnome Launch Box, an application which is very similar to Quicksilver for Mac OSX, has recieved support for the X server Composite extension. This results in eye-candy in the form of rounded edges and real translucency, making it closer to its OSX “brother”. I definitely suggest that you try it for your self, the screenshots do not fully express how amazing this application looks, and in my opinion it now feels closer to Quicksilver..