From part-way down the page:
USPS - 2006 Commemorative Stamps
"DC Comics Super Heroes Ten comic book heroes will be saluted on the 'DC Comics Super Heroes' stamps next summer. Half of the pane of 20 will be portraits of the characters; the other half will show individual comic book covers devoted to their exploits. The characters include Aquaman, Batman, The Flash, Green Arrow, Green Lantern, Hawkman, Plastic Man, Supergirl, Superman and Wonder Woman."
Here is a link to a jpeg of the stamps.
