Cult of Mac analysis of the WWDC 2013 logo reveals these thoughts:
Rounded rectangles …could be that Apple is bringing OS X’s Stacks to iOS…To me, this suggests iOS is finally getting Services, allowing apps in iOS to directly communicate with each other…
On the colorful icons:
Another possibility is that rumors are true and Apple intends on launching a colored range of iPhones in June.
..I do find the choice to make WWDC ‘reflect’ MMXIII interesting: to me, that implies second screen stuff, indicating to me that Apple might significantly beef up AirPlay, announcing new ways for your Mac, iPad, iPhone or Apple TV to communicate with one another.
And I thought it was just a logo.