I really hope this is a true leak. It's about time the iPhone goes 16:9. It bothered me when Jobs announced the original iPhone as being a 'widescreen iPod' when in fact it wasn't.
The current iPhone's oddball aspect ratio is looking rather oldy-timey compared to all the widescreen Android devices. So I welcome a true widescreen iPhone. It's been a long, long time coming.
I also like the shape of the overall frame. They shrunk the height of the home button area as much as possible. Obviously the earpiece area is also be the same height to maintain symmetry. To me it's a perfect front design (not crazy about the supposed leaked backs though)
Going forward Apple can finally have two standard aspects for its iOS devices: 3:2 (iPad) and 16:9 (iPhone, iPod, iTV).
I work with developers, and the new aspect isn't a big deal for them since retina upscaling is all done by now (and downscaling new apps for the 3GS is trivial in XCode). So adapting existing apps to the new resolution won't be a huge burden, especially considering how well XCode has supported new resolutions in the past.
Bring it on.