A few more recent reference points for those needing to know based on my recent stay (April 2011):
-"Executive Room" on 6th floor was my "upgrade" as SPG Gold
-"No room available" at check-in was accompanied be a "1 free drink" in the lounge with a note provided from the check-in clerk
-Hublot watches ($$$$$) for sale in lobby store
-Great location: close to the park, tourist-ridden Harrods, and most importantly, multiple tube stations
-Rooms in the x04 - x10 range seem to have the best view to the main blvd. out front (which is really the back based on where the entrance is), including the Mandarin Oriental and the Kuwait Embassy
-Car service (not taxi) to LHR was L85.00 including tips; billed to room before departure
-No bed bugs