Lots of info about the upcoming Diablo III has been leaked. Sounds like it's going to be a lot of fun.
It is also true that Beelzebub 3* features a story between the conflicts of Heaven and Hell and contains a very cool feature where every single item in the game can change between a "light" version and a "dark" version. However this was also one of the problems with the original version of the game. Other than the ability for any item to visually change from light to dark it didn't affect the actual stats of the item or change the gameplay in any way.
Not sure how legit this article is, but I know from a friend of a friend who works with Blizzard that they are in the process of making Diablo III. How close this article is to the truth, though, remains to be confirmed. But, it certainly makes the game sound fun.
*"Beelzebub" was used to replace "Diablo" througout the article. Read to find out the reasoning behind it.