For my own purposes, this suggestion is (at a minimum) aimed at the Alpha SLT-A99 and Cybershot RX1/RX1R cameras. THAT SAID, it is absolutley worth extending across the entire Alpha, NEX, and Cybershot product line.
I would very much like to see additional options for selecting aspect ratios in camera. Currently, both the a99 and RX1 are limited to the native 3:2, as well as 16:9. That said, I would like to purpose these aspect ratio offerings be exended to include 4:3, 5:4, and 1:1. I don't believe this to be an unreasonable request, as the current Cybershot RX100 and RX100II both already offer these additional aspect ratios.
While cropping a photo in post-produciton is always a possibility, I really feel that having the ability to actively compose a shot in the user's intended viewing format is a huge benefit. Furthermore, with the entire Sony camera lineup utilzing some form of live-view driven electronic viewfinder and/or rear LCD display, it is really quite silly not to offer these addtional aspect ratios. The electronic viewfinder, as opposed to traditional static optical finders, offers this type of viewing flexibility.
I sincerely hope to see this suggestion implemented in future firmware updates!