Based on other experiments, I gained the impression that opacity was not a property that is hardware accelerated on iPhone. However, Apple's own docs say it's "performance-enhanced" (whatever that means). This experiment is designed to isolate just the opacity property to see what is really going on. Turns out, it's pretty nice.
Click/touch the element below to see it fade out.
Click/touch the element below to initiate a fade-through of one element to the other, overlapping by 50%.