Wasn't this said in the pressers,also.
Sure, and I'm not an expert here but as I understand it, as a general rule they are protected for "speech" related to their duties as congress critters, whether they are on the floor or not.
However they are not always protected for all acts... when Jim McDermott (D, Baghdad) got the illegal tape he was successfully sued by Congressman Boehner in part 'cause getting an illegal tape wasn't in his job description.