I believe you're right about a 250kt limit but that only applies to Class "B" airspace.....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.
You want to complicate this further, there's a NOTAM that was issued shortly after 9/11 that restricts all movement to any ceiling around all the TRSA'a (Class B) areas. Normally (as in the Atlanta area) the Class B space is shaped like a upside down wedding cake so that any aircraft operating below a defined altitude inside of the Class B space did not have to report into Center or Approach.
After 9/11, The FAA extended the altitude exclusion to the ground. Now, the Class B space is no longer shaped like a upside down wedding cake but like a cylinder.
I believe that the space above the Class B areas was also extended to unlimited altitude for reporting and entry.
NeverGore