Answer:
   
   Traditional Judaism would not permit such mixed burial. However, there
   are circumstances where a non-Jewish cemetary sets aside a demarcated
   region of land to be used exclusively by Jews, in which case it is
   permissible for Jews to be buried in this section.
   
   Conservative Judaism holds with the traditional rules.
   
   Reform Judiasm, in principle, will bury non-Jewish spouses of Jews
   next to the Jewish spouse; they also bury as Jews some whom the more
   traditional movements would not consider Jews. However, if the Reform
   Jew is using a recognized Jewish cemetary, the latter is more likely
   to occur than the former (it all depends on that cemetary's practice,
   so ask).
   
   Conservative Judaism has issued a responsa dealing with the impacts of
   Reform Jewish practice. These subjects are discussed in "A Matter of
   Grave Concern: A Question of Mixed Burial" Rabbi Ben Zion Bergman,
   approved by the Committee of Jewish Law and Standards (CJLS), January
   30, 1991. Published in "Response 1991-2000" The Rabbinical Assembly,
   p.418-425