It's two squares, each with three rounded corners and one point, rotated +/- 45 degrees to point at each other.

maybe this picture will help: http://picbin.posterous.com/private/itGyiJrIJo

The :before and :after add one element of 60px x 60px on each side of the original element.

"border: 20px solid red;" and "border-radius: 50px 50px 0 50px;" makes these elements' border round on three sides and square on the bottom right. (of bottom left for the :after element)

"transform: rotate(-45deg);" and "transform: rotate(45deg);" turn the two elements so that their square corner meet in the middle, leaving one loop on each side.

The infinity sign caught me as the most interesting and apparently complex, but I love how simple the solution is