It will be a Winterboard theme. I looked here a little but didn't see that exact one. Here's a link there are some nice ones in the 1st dozen pages. Here's the link. http://macthemes.net/forum/viewforum.php?f=24
Darn I even looked through that thread cause I swear I saw it. Never new Carla was on Themeit & I was just looking through boss and noki user mods before I posted...
You know this is one area Apple could make a lot of money. Imagine if they let you buy and install lock screen themes as an in app purchase similar to newsstand?