The president of the United States is the most powerful person on earth, certain kinds of clothing communicate status and power, power is the ultimate aphrodisiac, yadda yadda yadda—so this was inevitable once Romney got the nom:

The ancestors of Team Mahonri Moriancumer designed and fabricated the very first Mormon temple garments in 1842.... we know a thing or two about these special undies. From the hand stitched masonic symbols, to the careful inspection of each garment, we care about the craftsmanship of this magical product. As a bonus, we're including special ceremonial instructions on wearing them "correctly," to ensure the most magical experience possible.
They have a men's line and a women's line at Mormon's Secret.