This has been an amusing thread with all the speculation appearing about the image. Here's the real origin:
I was trying to find royalty-free clipart or font characters to use, as I have in many of the other icons. Nothing was working out, so I dug through some of my old photos. I tested a few and settled on one from back when Savant and I had our wedding shower. All the wedding party (minus Skunkman, who wasn't in town yet) was standing on a boardwalk behind the Maiden of Honor's house.
And there you have it: a bunch of friends for the Friends icon.