I think that GW read the Interwebz and are trying to mess with our heads... either that or the colour of 6th ED will be GREEN...
Spines of WD look like a picture of a green marine
New painting guide is all about green marines (ok I exagerate, but their is a dark angel on the front)
and clearly as some sort of mind game, the chapter they choose to splash across their front page advertising transfers is bloody green like a Dark Angel (which caught me out until I looked more closely and saw it was clearly not a dark angel.)