20 amp Circuit, 15 amp switch that controls receptacles ok?
Dean MacGregor is correct.

Here is the pertinent National Electrical Code Article.


  Article 404.14(F) Cord- and Plug-Connected Loads.  Where a snap switch or control device is used to control cord- and plug-connected equipment on a general-purpose branch circuit, each snap switch or control device controlling receptacle outlets or cord connectors that are supplied by permanently connected cord pendants shall be rated at not less than the rating of the maximum permitted ampere rating or setting of the overcurrent device protecting the receptacles or cord connectors, as provided in 210.21(B).


So, basically the switch needs to be a 20 amp switch for multiple receptacles on a 20 amp circuit.