Scalado has introduced a simply brilliant mobile app - it's currently only Android and I don't know that they have plans to go iPhone, but it's so good I'm sure someone else will pick up the notion and do it at some point soon.
The idea is simple: Take a picture with your phone, but hold down the button for a while. Scalado looks at everything that's moving in you picture (by taking a bunch of frames), then gives you the opportunity to remove the moving elements. Usage? Shoot your sweetie standing by a sculpture in the park when tourists are walking by. Moving objects (the tourists) get removed and replaced with the real background behind them. The demo is freakin' awesome and the result is perfect. Take a picture of a beautiful scene where there are cars driving by ... remove them. Really really smart, hat's off lads.
http://www.scalado.com/pages/viewpage.action?pageId=7471561