Learn more about it here but the gist of it is this:  the Cassini probe will be taking a picture of Earth through the rings of Saturn on the afternoon of July 19th and NASA wants you to be in the picture (of course, you will be far too tiny to be seen in the actual shot!)

Happily, it is the Americas that will be facing Saturn at that time and that will be in sunlight... so that itsy, bitsy blue pixel in the finalized print will be of my side of the world.

Me? I will happily be outside my apartment at 3:27 pm, waving crazily at the Eastern sky at, what will appear to many to be absolutely nothing.  Not that I worry about what my neighbors will think... after all, if they aren't aware of what is going on, then they are simply not cool enough to be included in my first ever interplanetary photoshoot.