Join a worthy cause! Some gamer folk have created a Steam group appealing to Valve to say something (anything!) regarding the future of the Half-Life series. 10,000 members and counting, so far: http://steamcommunity.com/groups/messagetovalve
To those whose initial reaction to this is similar to my own, let me assure you this is not an attack on Valve, it's merely a heartfelt plea from a community of HL fans who want some assurance that their continuing loyalty to the series won't be taken for granted.
More than anything I think it poses some interesting questions about the obligations of companies like Valve to the fans who have contributed so much to their success. How long can internet communities remain active and engaged without fresh content (or even news thereof) from the companies they support? Is it okay for a company like Valve to be so guarded when their actions could make or break fansites, servers and mods?