It is an actual poster. One of several types of spam, which includes an [IMG]link-to-1-pixel-image[/IMG] -- you wouldn't see it because it's like, really small and stuff.
And I bet you ignored the actual text in your quote box -- 'cause you already read it the first time, so why bother again? Except for the sneaky spam... Which I now know to check for.
Quite annoying, I've seen it pop up in various places several times a month.