According to the list, it appears to be genuine as the domain name could not have been registered by a third-party, not to mention the emails of the staff appear to be accurate as well. Assuming that this list is accurate, some of the people working on the project includes Adam Foster, a hobbyist modder who was responsible for the Minerva mod; Kelly Bailey, a sound engineer/musician/game designer who worked on the main Half-Life game back in the day; David Speyrer, the supervisor for Half-Life 2 and Half-Life 2: Episode Two; Jeff Lane, Jim Hughes, Jean Rochfort, Karl Whinnie, Segiy Migdalskiy, Michael Coupland, and Ken Banks.
While it looks like Valve is well on their way in terms of developing the game, there’s really no telling when it would be announced, but if previous rumors are to be believed, perhaps an announcement in 2014 is possible.