A photo from a Wintek plant captured by a Weibo user has supported beliefs the iPhone 5 will have at least some design changes. Touch panels going through the contractor's quality assurance process support views that the next iPhone will have a larger screen. Along with the screen itself appearing bigger, the home button appears to now be an oval and suggests Apple might have 'squashed' the control, either to fit the larger screen or to accommodate interface needs.
Fits with other rumors, though it's still hard for me to believe it fits with Apple's plans. We'll likely see soon.