The unmanned lawnmower is nothing new, but we still think there's something downright iffy about arming a Roomba with sharp metal blades. That said, if you've been dying to get in on the action, SmartMow might be worth checking out. Set to hit the stores in Spring '09 for $749 (much cheaper than some other robo-mowers), the thing weighs 17 pounds, features three cutting blades, will cut around a sixth of an acre on a single charge (about 2-3 hours), and is auto-docking. As far as knowing where to mow, SmartMow eschews sci-fi grass detection algorithms and rudimentary art
