System Management Mode Article

I was reading this article on OsNews.com about using System Management Mode to circumvent OS security. At first, when I was reading the article, this sounded a lot like switching to Real Mode, which isn’t all that interesting. However, I came across the actual paper here that explained this a little more in depth. I was unaware that there were more operating modes than Real and Protected mode, apparently there is also a Virutal-8086 mode and the System Management Mode mentioned in the article. Interesting stuff.