By a very narrow margin, the book chosen for the December meetup is Old Man's War by John Scalzi!
The book was originally published in 2005 and was nominated for the Hugo Award for Best Novel in 2006. What's a little surprising is that Paramount bought the movie rights in 2011, though nothing seems to have come from it so far. There are subsequent books in this story, such as The Last Colony, The Ghost Brigade, and Zoe's Tale, with each of them are rather complete on their own.
As briefly described by the San Francisco Chronicle:
"With his wife dead and buried, and life nearly over at 75, John Perry takes the only logical course of action left: he joins the army. Now better known as the Colonial Defense Force (CDF), Perry's service-of-choice has extended its reach into interstellar space to pave the way for human colonization of other planets while fending off marauding aliens. The CDF has a trick up its sleeve that makes enlistment especially enticing for seniors: the promise of restoring their youth. After bonding with a group of fellow recruits who dub their clique the Old Farts, Perry finds himself in a new body crafted from his original DNA and upgraded for battle, including a brain-implanted computer. But all too quickly the Old Farts are separated, and Perry must fight for his life on various alien-infested battlegrounds. 'Scalzi's astonishingly proficient first novel reads like an original work by the late grand master, Robert A. Heinlein' Publishers Weekly 'Delivers fast-paced scenes of combat, and pays attention to the science underpinning his premise' San Francisco Chronicle"
You can find the book here on Amazon
You can find the book from Houston Public Library here