Celiac.com places MSG on its list of “safe foods list”. RecipeZaar.com does the same thing. The Gluten Free Bible (pages 18-19) expresses the same idea but adds the phrase “unless you are allergic to MSG (Chinese Restaurant Syndrome)”.
Many people have an allergic reaction to MSG. That reaction is somewhat like a gluten reaction but is actually not related. There is a small possibility that some brands of MSG contain wheat and that the allergen is not is not listed on the ingredients label.