Jeffrey Brown's Darth Vader and Son just went on pre-sale at Amazon. The book is scheduled for release in May.
Jeffrey also posted some sketches from the project on his blog.
A few months ago I interviewed Jeffrey and this is what he said about Darth Vader and Son:
It's called Darth Vader and son, and basically it's a collection of gags and vignettes about Darth Vader trying to raise a four year old Luke Skywalker - trying to get him to pick up his toys and teaching him how to ride a bike and stuff.