The girlfriend and I were just there about a week ago. They have the Cables down for going to the top of half dome right now, and a few of the trails are closed for the winter. We went for the weekend, and spent the first day out near mirror lake, and just wandering the valley. The second day, we decided to attempt going as far as we could on John Muir trail. There was still snow on the ground and the trail that goes along the Merced river was closed, sending you up the mountain side. Some really good views of the waterfalls to be had, even if some of the trails were "officially " closed. There were also a lot of Deer out, and they would even let us get within 5 feet or so of them. We also found a coyote out sunning himself. Let me know if you want to know anything else.
Enjoy yourself!
XTI w/battery grip | 50mm F2.5 macro | 18-55mm IS kit lens | 75-300mm F-5.6 USM III | 50mm F1.8 |lots o' filters