Hi afscout!
I've always heard this in the past but never actually seen it enforced. I've always viewed it as you wear what you are able to. According to: http://www.mninter.net/~blkeagle/camo.htm it isn't allowed and there is a quote on the page from: http://www.scribd.com/doc/8919606/Rules-and-Regulations-of-the-Boy-Scouts-of-America that is listed that the wear of uniforms that "imitate" uniforms of military units is strictly prohibited. Like I said I've never actually seen this enforced or been encouraged to wear anything else while at camp outs. I guess it all comes down to a judgment call.