Our prophet Muhammed, peace be upon Him, said that the honoring of a dead person is to bury him.
Therefore, it's like one of the service of sincerity and love for the one to pass away. And the honor of him is to bury him as soon as possible.
Yahya related to me from Malik from Nafi' that Abu Hurayra said, "Make your funerals speedy, for it is only good that you are advancing him towards, or evil that you are taking off your necks."
I will try to find more.
But I know there is no embalming which makes the body decay faster.
there is this too.. http://en.wikipedia.org/wiki/Islamic_funeral