Valve may have decided to spend their time and resources developing things other than Half-Life, and that's fine. But the Steam group "Call for Communication (Half-Life)" is quite politely requesting that they simply say so. To achieve the goal of more open communication, they've called for everyone with a brain and four fingers (W, A, D, *click*) to hop on Steam and load up Half-Life 2 this weekend.
The entire Steam community site seems to be down, so we'll just link you to an Escapist post from a few days ago about it. What more do you need to know, though? Just go play Half-Life 2, and hopefully Valve will have something nice to announce at E3 this year.
When do you think the conclusion to the series will actually come out? Could it possibly live up to expectations? Let us know in the comments or on Twitter.