convert opengis wkt to geometry?

After writing some code (stupidly without checking to see if there was 
code to do this already) to generate PostGIS SQL insert statements for 
simple geometry (wkt), I didn't check see if there is already something 
available to convert WKT strings into some R package geometry (sp?). 
Does anyone have any advice, hints, code (?) for converting the 
following OpenGIS strings into something useful in R:

POINT
MULTIPOINT
LINESTRING
MULTILINESTRING
POLYGON
MULTIPOLYGON
GEOMETRYCOLLECTION

Jeff.