Dan Abnett, as of now, is writing a Warhammer 40K book (Prospero Burns), his own book (not W40K, his own universe thingy), a W40K movie (probably done writing it, but he'll be needed for fixes I'm sure), and I've read that he's almost constantly helping someone with comic books.
I just want the bastard to write another Gaunt's Ghost novel, or another Titan book.
My friend assures me Karen Traviss is a good writer (if she broke canon or not, he can't say). Her Gears of War books... I liked the stories, but I wasn't sold on her style. Eh.
And though Zahn is a good writer, I'm not sure he deserves the 'ultimate writer' status people give him. I personally think Abnetts a load better, but most people are not fond of Warhammer, so... whatever and what not.