Does bitcoin have this?  Obviously the math would differ in bitcoin possibly, i'm speaking only in the functionality.  I would think this would be a good addition to multisignature...the idea of one key having more 'importance/relevance' than another with differing numbers of keys required based on their 'level'.

Maybe you have a situation such as two master keys, and 5 subkeys.  Where both master keys must sign, or one master key and 3 subkeys, or all 5 subkeys..etc etc.  The permutations are enormous obviously.

From http://passguardian.com/

Within http://passguardian.com/assets/1979_HowToShareASecret_Shamir.pdf

(4) By using tuples of polynomial values as Di pieces, we
can get a hierarchical scheme in which the number of
pieces needed to determine D depends on their importance.
For example, if we give the company's
president three values of q(x), each vice-president
two values of q(x), and each executive one value of
q(x), then a (3, n) threshold scheme enables checks to
be signed either by any three executives, or by any
two executives one of whom is a vice-president, or by
the president alone.