"Ladies and gentlemen, we have a new masthead. It's one of a series that will unfold over the near future. (Think of it as a visual blog unto itself.)" - PHB, 6/18/2008
The masthead series - "The Posthuman Blues Zone" - a frame of which is currently found on Mac's PHB blog, first appeared during the summer of last year. It is actually one of a series of frames which Mac posted sequentially in an endless loop, thereby telling a brief, silly, surreal, Rod-Serlingesque story. I think we (all) agreed it would make a great animation but, sadly, I never obtained the software and never had the time to learn how to create one.
It's also unfortunate that the frame currently appearing on the blog is the particular one it is. I would have been happier if it was the "door" with Mac's face in it. It could be worse though... as the actual last frame of the story was just a (now eerie) view of Mac's glasses (re: John Lennon) on the floor.
The comment of Mac's I remember most regarding the mastheads: "The jellyfish KICKS ASS."
The images below are the archived mastheads, in the sequence they appeared. Click on images for the full format. (Note: keep in mind that the frames were posted as an endless loop, so the first frame is both the beginning and end of the series.)