Double Eagle, by Dan Abnett. Well, it's a novel, by Abnett, so I really don't have to say more, but I will. As usual, the 40k setting is used to its fullest - utilizing the shared setting as well as adding plenty of original thought, as well it should be used. I'll note the interesting use of Herbert-style perspective shifts, which only a skilled author can really pull off (ie, even within mid-sentence at times). This is one of his novels, is another thing I should note, wherein it's more of an epic (with multiple, connected plotlines/characters) than one of his more closely focused novels. And his aerial combat scenes are just as cinematic and exciting as his more traditional action. Gush, gush, etc. Beer and pretzel scifi with lovely characters and a fast, engaging plot.

"The hardest part is cleaning the fur out of the damn rotor blades." Huh. Apparently, Phil says it's real.