Following Apple’s release of iOS 5.1 beta to developers last night, 9to5Mac dug right in and found some interesting code strings in the new beta referencing both the iPhone 5 and the iPad 3.

The two product IDs discovered were “iPhone 5,1″ and “iPad 3,3″, both of which represent significant hardware upgrades to existing iPhone and iPad hardware (the current iPhone 4S is 4,2, and the current iPad is 2,1; 2,2; or 2,3). iPad 3 references (3,1 and 3,2) have been spotted in iOS 5 before, but this is the first time the iPad 3,3 reference has been spotted.

Both the iPhone 5 and the iPad 3 are expected to take advantage of new custom chips from Apple, likely an A6 chip. The new hardware will likely debut in the iPad 3 first, which is expected sometime early next year (possibly with a Retina display in tow).

Numerous rumors have circulated about the iPhone 5, with most expecting a redesigned slimmer (possibly aluminum unibody) metal casing, and a possible 4″ screen. Further rumors suggest the iPhone 5 will be released next summer rather than in the fall.