It's so funny that smart but apparently under-busy people keep looking for some hidden meaning in the cake. From the Boingboing article:
Update 2: Fred sez, "The IE-team cake looked suspicious, what with the irregular white and black marks. The conspiracy theorist in me made me think about Morse code. I saw in the comments on the original blog that some people had looked at it and that there is no obvious morse code there. I couldn't be bothered to write a perl script to parse it depending on the starting place and direction of the message (cw or ccw), but it sure looks like some kind of message. I see, starting top left going cw, 'S E S / A T / (D:N:B) (U:V:A) / T N' I assume that someone else could properly decode this, so I suggest sending this as a challenge to all the would-be cryptographers and lovers of codes. What message has the IE-team hidden in the icing on the Firefox cake?"
The poor Mozilla guy who blogged about the cake had his server bandwidth charges fly through the roof with all the traffic. Sorry about that.