4.7-inch iPhone 6 and the 5.5-inch iPhone 6 Plus
Apple Hiring Chip Engineers for 'Orlando Design Center'
A number of the advertised positions relate to graphics chips and drivers, and it is possible that Apple may be working with AMD, which has an R&D and design facility in Orlando, in some capacity. Alternatively, Apple could be drawing on expertise at Qualcomm, which also has facilities in the area. In one job listing for a summer internship, Apple refers to the location as its "Orlando Design Center".
It appears that Apple has had at least a minor presence in Orlando for some time, but the recent job listings suggest that the company is undertaking a significant expansion of its team there.