Karen K has one of these on her site. Here is some info on it that is on the site as well.
"This is the LV VIP Ticket Cerise Keychain was given to VIP & top fashion journalists to gain access to the 2005 Spring-Summer Louis Vuitton Runway show. Takashi Murakami collaborated again with Marc Jacobs on the Spring-Summer 2005 Bags Collection to create this wonderful Keychain. The show took place on October 10th 2004 in Paris.
It measures 4" long. The Cerises should have been on all bags & this particular Keychain was going to be attached on all limited bags. Here's your chance to get this limited and highly rare Cerises Keychain since it has never and will never be sold in any LV boutique. "