Spam is popular in the Philippines, as well.
Also - we attended a traditional Chinese wedding in Chinatown (SF) a few years ago - one of the appetizers was made of Spam. And jellyfish. Ew.
I think it probably started back around WWII - our GI's ate it, cases were shipped around the world during and after the war to feed the hungry nations, etc.
(Actually, I've eaten quite a bit of it myself, back when I was a kid - one of my dad's favorite lunches was SLT - fried Spam, lettuce and tomato sandwiches!)
for those who just can't get enough SPAM trivia, here's a history link from the Hormel website:
http://media.hormel.com/templates/kn...emid=16&id=132