As we wrap up our 2009 Buyers’ Guide and look back on three months spent reviewing hundreds of applications, I’ve been pondering the ways in which Apple has changed the game in the mobile applications market. As some of our readers will know, I’m a very long-time PDA user, going back to the days when Palm was owned by U.S. Robotics. The device was actually called the “Pilot 1000” and had a whopping 128 KB of RAM—yes,…