The site's sources tell them that a new model is coming which is an iPad 4, comes in both black and white, comes in both Cellular and Wi-Fi, and is a more premium SKU that will join the 16GB, 32GB, and 64GB versions. There will also be 10-pack deals in both colors for educational institutions.
The P101 and P103 names are Apple’s internal nomenclature for the WiFi-only and Cellular-compatible fourth-generation iPads, respectively. Both of those models comes in 16GB, 32GB, and 64GB configurations. These storage sizes are known as “GOOD,” “BETTER,” and “BEST,” respectively. As you can see in our table above, Apple is preparing to release the additional “ULTIMATE” model. “ULTIMATE” frequently refers to the most premium or highest capacity model available. The “A” points to a black configuration, and “B” stands for the white option.
Interestingly, the report follows a tweet from @iNeal which noted that "We should be seeing 128GB iDevices soon. iOS 6.1 beta 5 has 128G system partition key in BuildManifest."