I just read this comic from Smashing Magazine last night. It seeks to explain the differences and similarities between XHTML 1.0, XHTML 2, HTML 4, HTML 5 and XHTML 5.
It’s a really well written comic that explains some very interesting concepts but keeps you intrigued through the well drawn pictures and good use of color. Even reading it last night on my iPod Touch I had no problems.
So, if you are looking for a good explanation about how these technologies are different and how stupidly named some of them are then this article is for you. I swear, I have to wonder if some of the people naming these technologies were drunk or something.