Well... Queens fly as fast as mutas, but see much further. One queen could stack with ten mutas for longer vision at the cost of one less muta's damage. That might be preferable to the standard stack of eleven mutas, and costs the same once the Queen's Nest is up. Might be worthwhile for builds that keep using mutalisk while teching to Hive.
I verified offline that the micro works (the stack doesn't separate), but I'm not nearly good enough to meaningfully experiment in a real match. Is a spotter queen in a muta stack possibly worth it?