This builds brings some big changes and a ton of bugfixes in preparation for beta.
The files data.mod and dialogue.mod expose in-game data for enterprising modders. Profiling tools were added to the console, and you can now opt-in to send Steam Marines play data to a server for tweaking/balance reasons (no private data sent; opt-in only!) This may also pave the way for a leaderboard or other online components.
Also, PEWPEW!