This script allows you to open AirDrop using Quicksilver.
Save this script somewhere that Quicksilver can find it, such as ~/Library/Scripts, then bring it up in the first pane and use the Run action.
If you want to get fancy, you can apply the AirDrop icon to the script file. To do so: (1) right click on AirDrop in the Finder sidebar and select Get Info from the contextual menu, (2) similarly open the Info window of your Open AirDrop.scpt file, then (3) click on the AirDrop icon in the first Info window, press Cmd-C to copy it, and finally (4) click on the generic script icon in the other Info window and press Cmd-V to paste the new icon.
tell application "Finder"
if exists window "AirDrop" then
tell application "System Events" to ¬
tell application process "Finder" to ¬
perform action "AXRaise" of ¬
(windows whose title is "AirDrop")
else if (count Finder windows) > 0 then
make new Finder window
tell application "System Events" to ¬
click menu item "AirDrop" of menu 1 of menu bar item ¬
"Go" of menu bar 1 of application process "Finder"
else
tell application "System Events" to ¬
click menu item "AirDrop" of menu 1 of menu bar item ¬
"Go" of menu bar 1 of application process "Finder"
end if
activate
end tell