This is now the picture that greets you when you head on over to Miku's Facebook page. This was posted about in other threads in this section, but I figured it might deserve a thread of its own for the sake of speculation.
In a way, it kind of reminds me of the cryptic semi-announcement of Miku and Toyota's collaboration. Hiroyuki Itoh said only about that that 'Miku's US debut will be in a week, and it will be spectacular'. Could this be a sign of news to come?
My best guess is that it's about English Miku's release, as I think they said they were shooting for spring 2012, and even if it comes out at the very end of spring, they still have to have time to drum up excitement for it. But that's only a guess. It could be something completely different.
The only thing that seems to be a sure bet is that it's related to Mikubook. But that seems to be it for now.