Here are a few internet sites we love:  a great site with an active and very helpful forum on the topic  another good forum site...more national in scope but has some good information  very active site with people who know Yosemite inside and out.  a very thorough site that covers the wonderful trail (and variations) from Lake Tahoe to Mt. Whitney. nice site from a regular poster on backpacking who has great experience in the Southern Sierra.  this one is full of great information about....yep--fly fishing in the high sierra!  What fun!  a wonderful personal approach to Yosemite by someone who was born there--son of a park naturalist.   the ultimate guru of ultralight backpacking
This website from volunteers from Desolation Wilderness... which has good information on current trail conditions. is the trip logs of a group of younger guys who backpack around Northern California.  Fun stuff, and some good trail information. has a good links page, as well as information about backpacking in lots of different areas.

Webcams?  try these:

And some National Park Sites:   Sequoia/Kings Canyon
And don't forget our National Forests:
And here is an NGO (non-governmental agency) that is working to protect the Sierra: