Looks like EagleCAD. The free version is quite useful (get the SparkFun parts library!). The only limits are the PCB size and layers (2), which are fine for almost anything you will want.
If you end up sending your design for professional boards, I recommend dorkbotPDX. Great price, and awesome quality. Also, he'll take your Eagle file, so you don't have to produce individual Gerber files.