No, it's not related to the iPhone 4. However, Sharp's Android 2.1-powered ISO3 handset does feature a 3.5-inch (960 x 640 resolution) retina display. Other features include: a "9.6 megapixel autofocus camera with image stabilization [and] one-seg TV tuner." Video after the break.
Though you won't find it sold outside Japan, you might eventually see one outside Japan thanks to support for Global Passport CDMA, meaning the IS03 can be used in countries that have operating CDMA networks -- the US, for example.[via Engadget]