Add groups that a contact belongs to the company field as CSVs

gistfile1.scpt

tell application "Address Book"
	
	set prefix to ", "
	
	repeat with p in (get people)
		
		set gs to ""
		repeat with g in (get p's groups)
			if (gs = "") then
				set gs to g's name
			else
				set gs to gs & prefix & g's name
			end if
		end repeat
		
		if (p's organization = missing value) then
			set p's organization to gs
		end if
		
	end repeat
end tell