Yoko Ono's "Grapefruit" show is up / recreated at the UC Berkeley Museum... I was just going to go to see a bit of history, and then I read this on the JL Museum site:

"Grapefruit" ... created the opportunity to write "Imagine": The collection of art works by Yoko Ono published in 1964 that contains instructions with poetical phrases. Art is created by readers' imagination and actions. John drew his inspiration from the instruction "Imagine" that arouse imagination, and it was set to one of the causes for the song "Imagine" to be produced.

Now I'm really excited to go. Whatever you may think of Yoko, John mentioned many times how aspects of her work inspired him (so I'm really curious to see the re-created show...)