I agree with mbondy. I have tried feeding them as treats before and although the jackson's eat them, some do seem to have trouble digesting them (they are harder for the cham to digest than superworms, for example). More nutritious would be silkworms or hornworms...
Mealworms, when gutloaded and calcium dusted, can form up to 10% of a chameleon's diet. Like superworms, they are higher in fat than other feeder choices and thus should not be a frequent part of the diet. As mentioned, their chinton content could also be a factor if mealworms are used in excess (unless the rest of the diet is largely soft bodied).