We're planning on adding support for range requests (which becomes equivalent to prefixes a la CouchDB). Is there a reason you need glob specifically?
well, for one example off the top of my head would be using geohashes for proximity in records... if you could glob every geohash with the same first 6-8 characters, you could do range queries pretty quickly.
I've considered similar for shard keys in terms of proximity related information.
Like, "show me all keys that match xyz∗ in this namespace"