The Minor Planet Center has wasted no time in assigning minor planet numbers to Pluto, 2003 UB313, and other Kuiper Belt Objects.
Additional identifications = Object Lowell Observatory = X
(136199) 2003 UB313
(136472) 2005 FY9
(136108) 2003 EL61
Minor Planet Designations
Andrew Lowe over at the Minor Planet Mailing List figured this out.
A tradition in the minor planets was to name the "special" numbers after something special: (8000) Isaac Newton, (20000) Varuna, (50000) Quaoar, etc. A great opportunity was lost when (100000) wasn't designated as Pluto.