Are we even sure it's a pentile display, as opposed to a "normal" AMOLED display?
As of late, all AMOLED displays have had a pen tile matrix aside from the Galaxy S2 series phones which carry the "plus" moniker. On a higher DPI/PPI display of this nature, the dithering effect may be minimal. But if you have a chance to compare the two at the same resolution, the older Samsung phones that Apple wants banned from sale (they have been for a while)
The best comparison is to have the two to compare, say a Galaxy S Vibrant (old phone but was the closest resemblance to the older iPhone and a Galaxy S2 series phone. Both have the same resolution (480x800) but the difference is major.
The largest OLED device I have is my PS Vita which has a rather nice display but I never bothered getting a good macro shot to see things up close as I did with the Retina Display on my iPod Touch.
If a newer device using OLED and a 720p resolution, the pen tile matrix may be rather hard to see but the "plus" versions use a standard RGB triad and are more power efficient.
If there's enough interest, I will bust out my DSLR and shoot a few photos of the different displays. The standard pen tile arrangement can be seen on Wikipedia. A close up of the HTC Nexus One.
My early experience with the older AMOLED displays were a bit hit & miss. Tough to see in direct sunlight. Dithering and color banding were other early problems but the technology showed much promise years ago.