According to some iOS 8 files found inside Xcode 6 SDK, the resolution of the iPhone 6 display will be 828 x 1472.
Although the number looks like someone pulled it out their backside, there seems to be some logic behind it. One of the files within the iOS 8 Springboard was optimized for a display resolution of 414 x 736. But since the SDK parses hardware resolution via point values, the actual resolution is usually double (or possibly triple) of that number. Hence, 828 x 1472.
828 x 1472 at 4.7-inch works out to be around 360PPI, which is more than the current iPhone display and 'Retina' enough. It would be a stretch at the purported 5.5-inch size, which is where Apple might go for 3x the 414 x 736 value, and reach 1242 x 2208, although we are now far too deep into speculation territory.
Whatever it is, we have about three weeks left now to find out for sure.
Given how ARM was founded by Apple and that Apple (to this date) still holds a large share of ARM, one can even go as far as saying that it's full Apple design.
Here's the Apple slogan: "Yesterday's technology at tomorrow's prices".
They hardly ever had any to begin with.