Since Blizzard has created World of WarCraft they have seemed to have slowed their release of games, possibly due to the success of World of WarCraft releasing a new game isn't as urgent since a constant stream of lots of money is constantly coming in every month.

Here is a list of Blizzard releases and their years leading up to World of WarCraft, I will just list their three main universes WarCraft, Diablo, and StarCraft and only those games that have been released.

WarCraft: Orcs and Humans - 1994

WarCraft II: Tides of Darkness - 1995

WarCraft II: Beyond the Dark Portal - 1996

Diablo - 1996

StarCraft - 1998

StarCraft: Brood War - 1998

WarCraft II: Tides of Darkness - 1999

Diablo II - 2000

Diablo II: Lord of Destruction - 2001

WarCraft III: Reign of Chaos - 2002

WarCraft III: The Frozen Throne - 2003

World of WarCraft - 2004

World of WarCraft: The Burning Crusade - 2007

As you can see, excluding expansion packs, Blizzard had always released a new game at the least every 2 years and sometimes even just one year.  But since Blizzard released World of WarCraft we have had no new games other than WoW Expansions released since 2004 and it is now 2008 with StarCraft II and Diablo III not being released until 2009 or 2010, which is 5 or 6 years after the last release of a new game.  World of WarCraft is great and all but I wish they would put a lot more development time into their other games as well so that we can continue to have a continuous stream of great Blizzard games.

I hadn't even really noticed this huge gap until I was playing WarCraft 3 and started thinking about all the times I had played the game and the different custom maps that were popular at different times and when I beta tested The Frozen Throne and I just thought to myself: "wow, this game really is 6 years old isn't it?"

they make so much money for them i dont think it really matters, plus alot of people love it more than their other games (im basing this on sales and account subscriptions of course)

Time to go back to one a year

I think it's more a matter of Blizzard not taking the money to make an entirly new whole division. Likely the money only went to increase a minimal amount of staff. Unfortunetly this conservative view means less games for us.

They are probably wanting to take their time and release a quality product. It will have HUGE expectations to meet. Luckily that Diablo 3 gameplay I saw was awesome. Definite a must buy for me.

You also have to consider a good amount of their staff goes to support and new content for WoW (not even considering expansion packs), this wasn't an issue with their previous games.

Well there is also the hopefully 2008 Wrath of the Lich King...

I play world of Warcraft only from blizzard, so it don't interest me much.

Blizzard needs to focus a bit more on new IP and new genre.
Games (Warcraft, Diablo...) that were new in 1994-97 were interesting because of the novelty factor for every gamers.
Now only the H&S and RTS fans will buy these games which will be great (3M sales guaranted) but they can't keep on serving the same things for ever.

What happened to Starcraft: Ghost? Was it a console release or did it get scrapped? What games have Blizzard put out on consoles? This is one thing to take into consideration, if they release games on other platforms too, it's straght away from their PC developement. Besides, there's also things as rising developent costs, which effect the developement times.