Re: ***Newbie "Must haves" for the 2010 Summit***
Even in July you'll want to bring a jacket and maybe some rain gear with you. Also pack some water and food for the trail. Some aspirin in case of high altitude headaches. I keep a small pack in my FJ at all times with all of these items, as well as a multi-tool, pen light, space blanket, fire starting stuff, etc.
And be sure to have extra batteries and a spare memory card for your camera, you will likely be taking hundreds of images while at the Summit.