Personally I think it's "nothing". Just because they own the "Half-Life" trade mark means little as they could specifically want to protect their "Half-Life 3" trade mark.
Recently there have been some sites and fan made creations that have pretended to be the real thing (not necessarily out of malice or anything). Might just be Valve making sure they have a legal route to pursue should something HL3 related pop up that they don't want tarnishing the name.
Recently there have been some sites and fan made creations that have pretended to be the real thing (not necessarily out of malice or anything). Might just be Valve making sure they have a legal route to pursue should something HL3 related pop up that they don't want tarnishing the name.