Recursive SELECT problem

Hi,

I'm trying to write a query to determine whether or not the current
login role has CREATEDB (or CREATEROLE) privileges, either directly or
inherited from a parent role.

The query:

SELECT EXISTS (SELECT 1 FROM pg_authid WHERE rolcreatedb = TRUE AND
pg_has_role(rolname, 'MEMBER')) AS has_createdb

does the job for CREATEDB, except that it doesn't honour rolinherit.
Anyone know how I can do this in pure SQL?

Thanks, Dave.