As KortoloB mentioned at the SG Reddit, we have not seen a new photoshoot since the TV Guide magazine photo shoot made on January 2011 for the launch of NBC's serie The Cape.
In most cases, a photo shoot is made to accompagny the launch of a new tv show or movie. Since Summer has not filmed something big enough to justify the making of a photoshoot, this is not surprising we have not seen a new one.
I've always liked the second one she did. It was just enough to cross that line into not revealing too much skin. Summer does have that natural beauty to her. Hard to see that in many of today's top A list stars.