When did Siam become Thailand?

Siam is the old name for Thailand and I have never known why and how that name change came about. A Bangkok academic is now petitioning the government to change the name back to Siam in order to make a step towards creating greater peace and unity in the nation. For those who are curious about the history of the name change from Siam to Thailand or wonder how on earth changing the country's name could do anything in the way of reconciling a divided nation, check out the Bangkok Post article "What's in a name?" The comments on this article are at least as interesting as the article itself as people weigh in on whether they think the change is a good idea.