<Update: The developers released eight new , pronouncing that the game is in Final Release Phase.>
For the first time in several years the dev team working on Black Mesa Source is finally going to release some new media. It's suspected that a new trailer will be what is unveiled.
Black Mesa Source is the total conversion of the original 1998 Half-Life to the Source engine, which began work in 2005. However, since 2009, almost nothing has been heard from the team, leading most fans to think that the game has slipped into vaporware status.
It'll be interesting to see what the devs have to show. Stay tuned.