These things always make me want to look stuff up...
91.117 (a)"...no person may operate an aircraft below 10,000 feet msl at an IAS of more than 250 knots: (b)"...bwlow 2,500 feet above the surface within 4 nm of the primary airport of a Class C or Class D airspace area at an IAS of more than 200 knots; (c)"...airspace underlying a Class B sirspace area designated for an airport or in a VFR corridor sesignated through a Class B airspace area at an IAS of mor than 200 knots.
By this, one could operate in controlled airspace between 10,000 msl and FL 180 in excess of 250 knots VFR.