Here's the ChangeLog:

Version 1.2.0
	-- numbers-only output (-n option)
	-- new style formatting (transmitted packets are 
	   shown on a separate line)
	-- updated log, now matches standard format:
	   (<Mon> <day> <HH:ii:ss> <program>[<pid>]: <entry>)
	-- extended -s option (more command automatically 
	   executed if we view all entries; -s=<n> shows last n	
	   entries from the log file
	-- log file moved to /var/log (now called constat.log)
	-- old style formatting option (-o): packets are shown on
	   the same line bandwidth is
	-- monitoring timer default value set to 30 seconds
	-- GNU-tilizing: configre, AUTHORS, INSTALL files added,
	   COPYRIGHT renamed to COPYING

Version 1.1.0
	-- new log format (more grep-friendly)
	-- added protocols: udplite, raw
	-- added unix sockets support
	-- added monitoring interval setting (-m[=<seconds>])
	-- added background mode (-b and -x options)
	-- updated man pages

Version 1.0.0
	-- added MTU to additional info
	-- improved -t option: now can display info for a specific
	   protocol or all at once, added Destination address and destination 
	   port columns
	-- added option to list available protocols (-p)
	-- added 'Press Ctrl-C to exit' message to the monitoring mode
	-- updated help and man pages

Version 0.9.0
	-- new arguments' parsing mechanism (totally re-written)
	-- logging added (-d -s)
	-- local addresses/ports view option added (-t)
	-- additional information view option added (-i)
	-- quiet mode added
	-- new documentation and man pages

Version 0.1.3
	-- added monitoring option (-m)
	-- rewritten mechanism of obtaining and processing data

Version 0.1.2
	-- added options to view sent/recieved in GB, KB (-g, -k)
	-- Updated --help
	-- Commented and structured source code a bit better

