I honestly think that at one time, Area 51 was the development and testing facilities for secret/new/alien technology. Now, however, I really think the US government is using Area 51 as their diversion, and the development and test facilities are elsewhere. By using Area 51 as the distraction, they were able to create a facility elsewhere that gets zero attention. They still feed/leak just enough to the media and public to keep that attention diverted...
I guess that would make Bush and Cheney sort of the Penn and Teller of the free world!