The Yosemite Climbing Association will host a 50 year anniversary reunion on Nov 8, 2008, to commemorate the first ascent of the Nose on El Capitan.
On the YCA's website, Ken Yager writes:
"If you are here for this event don't forget to check out our exhibit in the Yosemite Museum (open everyday 10:00 - 4:00). Granite Frontiers: A Century of Yosemite Climbing will be up through November 9th. The exhibit has been the most popular exhibit shown in Yosemite and it will travel to other venues next year.
"During all this we are receiving more donated artifacts and trying to keep up on the cataloging. It is a lot of work and we appreciate your donations. Without them it would not be possible. If you haven't made a contribution lately, please consider a donation. We are a tax-exempt organization."

Warren and Powell. Image courtesy of the Yosemite Climbing Association
While you're in the Valley, stop by the Yosemite post office and get this special pictorial stamp cancellation:
You can also mail a letter or postcard to the post office and request the special stamp. Please send a SASE, attention: Postmaster, to the post office in Yosemite Valley. If you have further questions about the special stamp, please contact the Yosemite office directly.
