Upon right clicking the page and choosing view source I was shocked and amazed.
The first thing teachers drum into your head is that the first line of any HMTL or xHTML page is a doctype declaration which is missing from the WoW homepage.
It surprised me that a company as major as Blizzard has web designers that leave something out that even a beginner student in web design knows should be there 100% of the time.
This really is a bug in that its faulty code that should be fixed so it validates correctly. A forum mod really should bring this to the attention of the head web designer.