Blair Lazar has now done a "16 Million Reserve", registered at 6,000,000 Scoville. Since his 2 A.M. sauce is already insanely hot at 600,000, this would seem over the top.
Happily for the safety of the world, it's limited edition - 999 bottles of an ounce each, or a total production of just over 62 pounds. At $300 per ounce, that's also pretty expensive, but given that it's not actually a sauce at all - it's purified, crystalline capsaicin for use as a food additive - this should be the end of the escalating heat wars.
EDIT: as
EDIT: That may be because of this new article: Chillies heated ancient cuisine, apparently showing Ancient Ecuadorans of 400BC using the spice.