This is the Starfire Space Cannon. It's been built and tested by Richard Graf and his cohorts up in Cochrane, Canada. The goal of the Starfire cannon is to launch small, lawn dart-sized projectiles into orbit as vehicles for small satellites. Of course, there is a small problem with this sort of project: governments, even happy-go-lucky Canadian ones, don't much like it when you own a cannon capable of starting an international incident.
Graf is of the opinion that space is for everyone, and he means to get us there, one cannon shell at a time. To that end, he's constructed a 45-foot long cannon with an eight-inch bore. To further speed his projectiles into space, he's designed his cannon to fire its propellant in sequential charges as the shell — er, launch vehicle — travels down the barrel. Graf says this will break up the massive G forces which a projectile endures as it's fired.
While that may be true, we're not entirely sure that Graf's cannon has enough power to reach escape velocity. Currently, the Starfire cannon has a muzzle velocity of 1.5 kilometers per second. First of all, that's crazy. Secondly, it could conceivably get his projectiles as high as 100 kilometers up, but that's only the very lowest threshold of space. To achieve an orbit where it could safely deploy a satellite, the Starfire cannon would need a whole lot more power. As it stands, Graf would likely win any Punkin' Chunkin' that he entered, or, you know, start a war by accidentally firing upon North Korea.
If you'd like to fund Graf's quest for backyard space-cannon firings, he's currently seeking $65,000 Canadian through Kickstarter.