The Galaxy Tab Android tablet has landed. The greatly anticipated Samsung device represents what might be the greatest challenge yet to the Apple iPad’s months-long dominance in the newly redefined tablet market. The Galaxy Tab is smaller and lighter than the iPad. The Galaxy has two cameras, runs Flash and offers multitasking. It’s attracted attention from publishers seeking to put their content on a mobile device, and it’s less expensive than the iPad. However, it has a smaller, seven-inch screen, a measurement upon which Apple CEO Steve Jobs heaped scorn recently as being inadequate.