+1 I could really use this feature too.
I have a hash where keys are frequently being added and removed, but
existing keys do not change very often.
If I WATCH the top level key, then my MULTI/EXECs will fail
frequently, even though I am only interested in
updating an existing hash key in the hash.
The only workaround I can think of is to redundantly store the hash
keys as simple key-value pairs, and watch
these keys, but this is very wasteful in terms of memory.