I searched under "can I substitute sorghum flour" and quite a few things popped up, further down the search page results it looked as if one can use it as a sub for rice flour, and vice versa.

This was only one of the links that could prove helpful, especially if you look around more (I didn't have time)...scroll down to "Sorghum Flour" on this list of all sorts of flours.
http://www.foodsubs.com/Flournw.html

I use this as a general rule of thumb when dealing with non-gluten flours:
1. For cookies, replace 1 cup of wheat flour with 7/8 cup sorghum flour + 1/8 cup coconut flour.
2. For Brownies, make it 3/4 cup sorghum flour + 1/4 cup coconut flour.

For amounts that are not an even 1 cup, eyeball it. More coconut flour will make the finished product more dense.

Sorghum has a sweet flavor to me, so I would use it primarily in spicy things (like gingerbread cookies, or spice brownies).

I bake gluten free and use sorghum all the time. I would just use it as you would regular flour substitute a 1/4 or 1/2 cup for regular flour. Also check Indian recipes such as sorghum roti. Mmm..yum.

Here's a link to some sorghum recipes, courtesy of the Nebraska Grain Sorghum Board. I found the site when I ran a Google search for "sorghum chocolate chip cookies". The chocolate chip cookie recipe happens to be excellent for a gluten-free cookie. Not all, but most of the recipes listed are gluten-free.

http://www.sorghum.state.ne.us/publications/sorghumrecipes.htm

Actually it appears that only the cranberry bread recipe in the link I posted above is not gluten free, so there's a pretty good collection of stuff. I think I'll try the Chocolate Sorghum Buttermilk Cake next.

The thing with any gluten-free flour is that you can't just use it alone- you need to use a combination of gluten-free flours to get good results. (And typically an ingredient that will act like gluten- either guar gum or xanthan gum). So if you're looking for a recipe with ONLY sorghum flour, you're probably going to be disappointed. But, I've found that sorghum flour is one of the very best flours for GF baking when combined correctly, and I use it in most of my GF baked goods, typically mixed with rice flour (brown and/or white), and tapioca flour or corn starch.

I made GlutenFree Goddess' Gluten free brownies with pecan meal this weekend and they were AMAZING! The ingredients were pretty straightforward and they use sorghum flour and pecan meal.

You can find the recipe here: http://glutenfreegoddess.blogspot.com/2008/12/chocolate-pecan-brownies.html

Enjoy!