Todd McFarlane has posted images of some Spawn concept art on his Facebook page, including these two images, one of Sam and Twitch, and another of an exterior shot.  "Here are some early images of a few key characters and a rough of a city street...," he posted. 

McFarlane indicated that the art samples were only a small sample of a much larger art trove for upcoming Spawn animation, and said that more info would be coming soon, including, possibly, voice tracks and an image of Spawn himself.

There was an Emmy-winning Spawn animated series on HBO for three seasons, and a live action theatrical feature in 1997, but there’s been nothing new in the intervening years. 

McFarlane said last year that he was working on a live action Spawn feature (see "McFarlane Working on 'Spawn' Feature"), which would be low budget with a minimum of special effects.  This animation project appears to be something completely different; no word on what’s happened to the live action feature.