Snowballing speculation over a NASA press conference

Well, here we go again. I don't generally like to talk about NASA press conferences before they happen because I don't want to promote baseless rumor-mongering. In this case, though, I feel I have to write something to prevent speculation! Here's the scoop: NASA released the news that a press conference will be held on Thursday at 14:00 ET, saying that the conference will "discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life." That, of course, set everyone speculating. The very popular news site Kottke.org actually has a decent line of evidence on the topic of the conference, though a sensational headline of "Has NASA discovered extraterrestrial life?" Gawker has a post up about this as well, and social networks like reddit have a lot of people talking, too. Other examples abound. So what's the press conference about? I don't know, to be honest, beyond ...