You actually see a fallback image with the transparent character on top in all other browsers, since there isn't support for unicode characters this high (U+1F3E9). If you highlight and right click on the love hotel character on OS X you'll see "Search google for '🏩'" with the full color love hotel character.
I guess it's only a matter of time before "pile of poo" (U+1F4A9) gets its own domain, too.
Or http://☃.net if you prefer.
Interestingly, I observe my font is rendering the snowflakes around the snowman as pentagons. Some font designer needs to study some more science.
I learned the answer after reading a great talk (in blog post form) about the ever-growing unicode character set: http://www.reigndesign.com/blog/love-hotels-and-unicode/