Thanks for the post. (this thread should have gone in the General section)
Of course I used google and wikipedia. You can't tell I'm resonabily tech savy by how I wrote the questions? Anyway, Debian is a good place to start looking. Seems to be like Debian 4.0.
Since Linux was around since the early 1990s, I don't think Maemo can be easily called "It's a Linux" since Linux has been constantly updated since the introduction.