43addcit reports that Panasonic may release additional information or officially announce their upcoming Lumix S1/S1R full-frame mirrorless cameras on January 31st. The official announcement has been rumored for the January-February timeframe and Panasonic recently confirmed that shipping will start at the end of March.
Recap of everything we know so far for the Panasonic S1/S1R cameras can be found here.