I read the manga and am currently watching the anime.
Ryuk once commented that users of the Death Note can neither go to heaven nor hell. (Though one source claimed that this was only a fake rule that Ryuk wrote/spoke.)
This suggests Light becomes a Shinigami. If so, why does Light not continue the work he began on Earth? Does L (who also touched the Death Note) become a Shinigami as well, somehow preventing Light from doing his deeds?