I found this article that talks about the different types of immersion. Although very, very briefly. But with all this talk of Immersion, I thought it would be good to post this incredibly short article up.
http://www.designersnotebook.com/Columns/063_Postmodernism/063_postmodernism.htm
It is specifically addressing how Postmodernism (meaning, in this case, self-referencing to declare what you are playing is, in fact, a game) is detrimental to immersion in serious games (aka, MGS and not Secret of Monkey Island) and not just playful jokes.