I totally didn't know that! That's awesome!
Here's one I found with four components: http://solomonsmusic.net/FM_Cr...
I am curious how that tiny antenna can produce enough energy to drive even a crystal earpiece. Most crystal radios need huge antennae, don't they? And from the writeup it looks like the FM decoding more or less happens by accident as a side effect of signal interference.
If this really works, I reckon it should be possible to build a miniaturised FM crystal set into a pair of headphones. I wonder if you could do stereo?