We just submitted the new build of the NS2 alpha to Valve so it should be auto-updating shortly!

Technical

Changed collision detection to use the Havok engine

Optimized trace ray and sweep capsule tests

Fixed bug where keys could get stuck down after a frame hitch

Fixed bug where players could not be removed from the scoreboard after they left the game

Fixed bug where bots would not be properly removed from the server

Fixed crash on exit when trying to run the game without Steam running

Fixed bug where particle systems weren't properly occlusion culled

Fixed hardware cursors not being properly released on shutdown

Fixed bugs with the occlusion culling system not properly determining if something is visible

Changed the "Couldn't Connect" error message to be more descriptive

Added net_messages console command to log network messages received

Added r_gui console command to enable/disable drawing the GUI

Added the ability to include PROFILE markers in script code

Added support for Lua GUIs on models (i.e. ammo display on the Rifle)

Gameplay

Completely re-did marine, alien and "shared" (waypoints, chat, death messages, etc.) interfaces in Lua (was in flash). You should see noticeable frame-rate improvements.

Added very basic bots for load testing ("dev 1" at server, "addbots #" or "removebots #"

Armory "buy" menu fully client-side now so it's much more responsive

Hydras now build smoothly

MACs and Drifters now cost energy to produce (further eliminating spam and overly simplistic defense)

Sentries turn off completely without power

Power nodes have almost-dead and dead electricity/sparking effects

Reduced number of network messages and footstep sounds dramatically

Networking optimizations

Power nodes work on level change

Structure flinch animations fixed

Changing weapons as marine is now faster and more reponsive

Added basic pathing for bots (when commanding)

Fixed MAC welding effects

Skulk leap now requires research (on the Whip, coming soon)

Fixed "doubling up" of some sounds

Also, here's the changelog from the previous version which we released previously (Build 153):

Technical

Fixed the net_lag console command

Fixed the player limit on servers

Fixed bug where the server could send two updates with the same time

Fixed bug where attempting to connect to a nonexistent server would not properly fail

Fixed issue where time would not advance uniformly on the client causing motion to appear jerky

Fixed bug where disconnecting and then reconnecting to a server could put the game in an incorrect state

Fixed bug where clients sometimes couldn't move when when connected to a server

Added support for extrapolation past the last update from the server

Added a timeout for authenticating with the Steam servers

Added displaying the average server tick rate with the net_stats console command

Gameplay

Fixed problem where infinite MACs and Drifters could be built and cause problems (now limited to 25 units in an area)

Fixed power node in tram marine expansion

Power nodes can be repaired properly again

Fixed extractor multiple upgrade bugs

Fixed hive sight drawing incorrectly

Fixed sentry accuracy problems

Fixed lowered server CPU performance when using sentries

Fixed problem with power nodes on map reset

Fixed missing text tooltips for commander UIs

Fixed build harvester problem from gestate menu

Fixed death message weirdness

Fixed ns2_junction minimap

Changed power nodes to pulse red when out of power (makes it more obvious)

Lots more coming soon. Stay tuned!