More specifics about the directive from Sony regarding 3D content being capped at 720p have come to light. The issue isn’t actually with the PlayStation 3 itself, but rather the HDMI 1.4 standard which limits resolutions to 720p 60fps, 720p 50fps, and 1080p 24fps.
No one would really want to play any type of a fast moving title 3D or otherwise at 24 frames per second, and this means that the logical choice is to limit the titles to 720p where developers can take advantage of the higher frame rates. The decision by Sony to enforce this restriction is actually logical, given the design of the PS3.
It is possible to achieve 1080p resolutions with a dual DVI setup to achieve higher frame rates as done with graphics adapters on the PC platform; and while apparently the GPU inside of the PS3 is technically able to achieve this kind of output, it isn’t supported, as there is no second video output connector supported on the new 3D TVs.
The decision to enforce this restriction might sound rather draconian; the reality is there just isn’t another option given the current hardware design combined with the 3D TVs that are being released. However, we honestly doubt that most players will ever notice; and would you want to play 3D games at 24 fps, anyway? 24fps is good for 3D movie watching, but not for gaming.