Once upon a time, tablets came in one size the 9.7-inch iPad, and and cost anywhere from $500 for a WiFi0-only model to $800 for a 3G model with added storage. When Research in Motion announced its first 7-inch PlayBook tablet, then-Apple CEO Steve Jobs famously scoffed at their prospects in an epic rant on an Apple earnings call. In the two years since the first iPad, however, tablet configurations and price points have proliferated to the point where manufacturers now feel compelled to offer a full line of devices, hitting multiple screen sizes and multiple price points. Having proved Jobs wrong with the success of its $199, 7-inch Kindle Fire, Amazon is now prepping a 10-inch model, according to supply-chain reports. Samsung offers 7-inch, 9-inch and 10-inch versions of its Galaxy Tab, while Barnes & Noble now offers four different versions of the Nook. Even Apple is now exploring the possibility of introducing a lower-priced, 8-inch iPad Mini to better compete with the Kindle Fire. Not even Steve Jobs called ’em right all the time.