Yeah - my initial reaction was to think of Gen. 3:19, upon which the burial rite "ashes to ashes, dust to dust" is based. If we are formed from the dust and will return to the dust as a natural process, I fail to see the "sin" in speeding up the process through cremation.
But, again, I have never really studied the issue, so wanted to get the views of those who may be more knowledgeable than myself on this topic.