There's a new Wallace & Gromit short coming in July. Sadly, it's only going to be a minute long, so we can't expect something as grand as The Wrong Trousers or Matter of Loaf and Death.
A short clip, a behind the scenes featurette and more details are available here: http://www.bleedingcool.com/2012/05/05/brief-clip-some-behindthescens-from-wallace-gromit/
There are rumours flying around that Peter Sallis isn't voicing Wallace in this one. It sure does sound like the guy who did the voice in the Telltale episodes. Pretty cool to see him voice the actual claymation Wallace model.