UPDATE: I've been working hard at this, and I finally have the Best-Ever Gluten-Free Challah Recipe -- it's the only one you'll ever need.
NOTE: I've started using a NEW recipe that I'm pretty fond of, although this one still holds a place close to my heart. Check out this other gluten-free challah recipe from MyJewishLearning.com.
Wait, something else I need to mention: My challah isn't braided. Most gluten-free challah isn't braided. Why? Because the dough just isn't the right consistency for braiding, unfortunately.
That being said, does challah have to be braided to be challah?
I can't seem to find anything that says that the braiding is a necessity of challah. The reason we have two loaves of challah for Shabbat are clutch in commemorating the double portion of manna that HaShem provided the Israelites in the desert (Exodus 16:4-30). The various shapes and stylings of challot have a varied history.
Evidently, according to author Gil Marks, most Ashkenazim used their weekday round or rectangular loaves for Shabbat, but German Jews began to create ova, braided loaves modeled on a "popular Teutonic bread." (Whatever that means.) This shape became the norm, although many Middle Eastern and Sephardic Jews still use a round, flat bread or plain rectangular loaves for their Shabbat challot.