Sky burials are reserved for important people. In fact the pecking order (no pun intended) for burials is as follows: 1) the stupa (usually reserved for high order lamas and abbots and usually placed within monasteries). The lama's tomb (or stupa) sits atop a structure five layers high representing (below it) the five types of burial; 2) sky burial (reserved for important people); 3) cremation; 4) water - usually for babies as they are placed in the water (this is one of the reasons why historically Tibetan people have not liked nor eaten much fish. However, that's changing as the influx of Chinese grows stronger (they love fish); and 5) the ground - the lowest order as you are placed closer to hell.

The process for a sky burial is interesting. They drain the body of fluids; cut the body into pieces; separate the meat from the bones; crush the bones and offer them to the vultures. The reason they do this is they figure that if they give the meat first to the vultures, they won't bother to come back and get the bones.

According to Tibetan lore, the last thing we're able to give to god is our body; therefore the vulture comes down, picks up whatever is left of your body and takes it up to the heavens, to be disposed of who knows where. I rather like that concept. And then, of course, reincarnation kicks in.