After I upgraded to 10.5.6 QS crashed for me too, but it was **not** the Calculator Plugin (working fine btw!), but a corrupted shelf entry. The Console showed there was a __CFFromUTF8 originating from [QSLibrarian loadShelfArrays], so I went to ~/Library/Application Support/Quicksilver/ and renamed that folder Shelves/ to Shelves (disabled) => now it's working again!
Even the shelves plugin running again (but of course my previous shelf entries are now gone)... Hope this helps, best, Michael
