I think I have partly answered my question- This seems to be where the term came from, but who and what were the 1980s groups? Did anything ever get beyond the talk?
"At the Ecole des Beaux Arts in Paris, the world's top architectural school in the 19th c., professors would circulate with carts to collect final plans. Students would jump on the cart with their work, frantically finishing up their drawings." In the mid-1980s community planners had adopted the name to describe a multiday community planning session. "A charrette assembles a multidisciplinary team typically consisting of planners, citizens, city officials, architects, landscape architects, transportation engineers, parks and recreation officials and other stakeholders to create a design and implementation plan. One strategy ...is tme compression ..."