Apple's Jonathan Ive, who took over recently as Apple's overall human interface manager, is said to have been sitting in on the design review sessions that the company's human interface (mobile software) teams hold regularly. According to the Wall Street Journal (WSJ), Ive is pushing for a "flat design" in iOS 7, that has been described as "starker and simpler".
Ive's ability to influence iOS' look is an indication that the internal dynamics of the company is undergoing a significant change towards an increase in “collaboration across hardware, software and services," -- starting with design. This company goal was stated by Apple CEO, Tim Cook, when Scott Forstall was forced to leave the company last year.
Source: Wall Street Journal