The AppleScript Spotlight importer installation fails since the 
app/binary/package of the Script Editor.app (whatever you'd prefer) has been 
moved and renamed:

In 10.5.x it is:
/Applications/AppleScript/Script Editor.app

In 10.6.x it changed to:
/Applications/Utilities/AppleScript Editor.app

So the installation script would need to accommodate both locations.

Thus said, even copying it manually does not make it work. Something else 
necessary for 10.6?

Steps I've tried:
1. Created directory with:
  sudo mkdir -m 755 -p /Applications/Utilities/AppleScript\ Editor.app/Contents/Library/Spotlight

2. Copied AppleScript.mdimporter to:
  /Applications/Utilities/AppleScript Editor.app/Contents/Library/Spotlight/AppleScript.mdimporter

3. Tried to register with: 
  su ${USER} -c "/usr/bin/mdimport -r '/Applications/Utilities/AppleScript\ Editor.app/Contents/Library/Spotlight/AppleScript.mdimporter'"

Listing the currently active mdimporters with "mdimport -L" shows that the 
bundle did *not* register.
system.log says nothing.
Searching for a known-string-inside-an-AppleScript.scpt yields nothing, so most 
likely the importer isn't working at all.
If because of not registering or because of another general problem, I'm not 
able to say.