If you're talking about the Computer History Museum I'm thinking you are, it's not in San Jose, it's in Mountain View. It's actually in the old Silicon Graphics headquarters.
http://www.computerhistory.org/
It's been open to the public for a long time. I was there last in the Summer of 2008 and they had the two player Computer Space and a couple Galaxy Games but they weren't behind glass like that, just some railing. That video game display looks new as last time I was there it was just a rack of a few consoles. They're always adding more stuff. The personal robots were all in their own glass cubes when I last visited. Maybe the new video game display just opened or they re-opened to the public after a couple months for schools and organizations only? Nice to see the Babbage difference engine is still there. Are they still giving demonstrations of its operation? The interesting thing about that machine is it was constructed using materials and methods accurate to the time in which Babbage attempted construction, proving that it could have been done.
Pay no attention to the dork in the middle of the Cray-1.
There's a lot there to check out. They have an Enigma machine, some early prototype mice, an Apple I. You really can burn a few hours there easy.