Apple has begun putting up internal banners for WWDC at Moscone Center. Apple had previously confirmed that it would announce iOS 7 at WWDC.
The design of the banner is very different to previous banners of iOS7 and shows the minimalistic feel that iOS 7 will have. Jonathon Ive took over design of iOS 7 toward the end of last year and is said to be interested in simplifying the design of iOS and make it look more like the physical design of Apple products.
At the same time a banner for Mac OS X 10.9 also appeared and also carriers a simple design unlike previous years. Apple will also announce 10.9 at WWDC.
The font on both banners appears to be Helvetica Neue Ultra Light, an extremely thin variant of Helvetica, Helvetica is the default font for all iPhone, iPad and iPod's. It will be interesting to see if Apple start using this Neue Ultra Light version with iOS 7 and OS X