The Black Mesa Research Facility website is now hosting a mysterious countdown clock against a backdrop of wavering color bars, static, beeps, and a few glimpses of Half-Life's notorious G-Man. The clock appeared sometime yesterday—linked by the Black Mesa mod site—and represents the number of days, hours, and minutes until the clock runs out and... something happens, we presume.
The countdown could signify a number of things. It could be the announcement of Black Mesa's appearance on Steam, as was promised quite some time ago. It could be a teaser, or trailer (or a teaser for a trailer, as that sometimes happens) for the next portion of Black Mesa, since the original game left off with Gordon's entrance to the dimension of Xen. Maybe it's the release of the Xen portion itself.
Or, it could be an announcement Half-Life 3, because everything could be an announcement for Half-Life 3. Right? We'll find out on May 5 when we rise and shine.