This isnt an official Valve Level but by a very talanted group of people who are making episodic levels for hl2.. they released the first level yesterday.. which you can d/l for free.. I played it for about an hr, on high difficulty and it was some fucking fun.. very hard..
anyhow head on over to
http://developer.valvesoftware.com/wiki/MINERVA
for more and d/l the level.