Gears of War 3? Apparently, there were enough to fill up an entire novel -- the recently announced Gears of War: Anvil Gate. The book, which focuses on a Locust attack on the titular settlement of Anvil Gate following the previous game in the series, was penned by prolific Gears scribe Karen Traviss.
Gears of War: Anvil Gate will arrive in bookstores on August 31, which should give you plenty of time to study up before Gears the Third comes out. Unless you're like, the slowest reader ever. In which case, you should go to bed, dude. It's already tomorrow.