Slowly your tent develops its own little pedestal. There are two problems with this. First, your tent-stakes will start to melt out and second, the edges of the insulated tent floor will begin to melt-out.In the snow, tent-stakes should be buried in a T-slot instead of buried vertically. Work-harden the snow to make sure that the stakes stay in place. If there is any metal showing from a stake, it becomes more likely that the stake will melt-out. Warmth radiates through metal. Making sure that a placement is solidly work-hardened will decrease the likelihood of a stake melting out in the short term.
When the snow underneath the tent starts to melt-out, it tends to do so from the edges. Over the course of a couple of days the melt-out will force the tent's occupants to cuddle more and more closely together. The sides of the tent become a trough, eating up all the extra equipment.
If you plan to camp in a given location for a longer period of time, the trick to avoiding problems is to pile snow all around your tent. Pile the snow heavily along the sides of the tent and over the snow-stakes. If the edges of the tent are well-covered, the problems that arise with longer camps become less prevalent.
--Jason D. Martin