I was just there back in July, and had a blast. It was my first time in the Smokies, and I'll be going back, without a doubt.
Little River Outfitters has a forum you can take a look at for some info. I found it after I came back home. I wish I would have found it before I went.
http://littleriveroutfitters.com/forum/index.php
When I was down there, I purchased " The Fly Fisherman's Guide To The Great Smoky Mountains National Park", by H. Lea Lawrence. I actually bought the book at the Gatlinburg Visitor Center. The Park visitors centers didn't carry this book, but had another one, the title escapes me now. I am happy with this book though, and read it over the coarse of two evenings while there. It also has two different park maps in the back.
The park is actually pretty easy to fish, with plenty of pull offs for the upper Little Pigeon river (nothing more than a stream once your in the park) along Rt. 441 from the park boundary on up to around New Found Gap. Also, there are plenty of places to pull off for the Little River along Rt. 321. The Little River is one of the larger waters in the park, and frankly is downright dangerous in many places. These are all fast, high gradient waters. A wading staff is highly recommended.