Answer:
   
   While tattooing is against Jewish law, there is also a principle that
   a person can repent up until the moment of death. The assumption is
   that the person did teshuva (repented) before they died, and so there
   should be no problem burying them in a Jewish cemetery. Of course, it
   is probably appropriate to CYLAR* (appropriate rabbi) as well as
   CYLAFD* (appropriate funeral director). There is a story that relates
   to this (courtesy Micha Berger):
   
     There was a ba'al teshuvah (returnee to Orthodoxy) who went to the
     mikvah on erev Yom Kippur. Before discovering Judaism, he got a
     tatoo on his upper arm. By the time of the story he was learning in
     a yeshiva and quite embarassed of it. An older man saw how this
     teen was standing with that arm toward the wall. And then "just
     happened" to throw his towel over that shoulder. In short,
     squiriming around to make the tatoo less noticable. The man walked
     over to the boy and showed him his arm. "See I too have a tatoo. I
     wear it with pride. It reminds me where I have been, and how far I
     have come."
     
   Note that deliberate tattooing is against Jewish law: "Do not lacerate
   your flesh for the dead, do not tattoo yourselves." (Lev. 19:28).
   Cutting of the flesh and tattooing was associated with idolatrous
   usages among the Canaanites. Many traditional mortuaries and
   cemeteries will not officiate at a funeral of one who is tattooed.
   However, since this practice has become more and more common, even
   among Jews, the policies may become more relaxed with time. If you
   intend to be interred in a traditional Jewish cemetery, you should
   contact them to verify their policies.
   
   Do remember: today, tattoos are in; tomorrow they might not be. And
   though there are ways to remove them, why risk the potential cost and
   pain? Let the beauty of your soul be the example people will see and
   not a "heart with Mom" inside. And take the money you would have spent
   on this body art and give it to a noble cause.
   
   *[CYL = "Consult your local"]