I was just reading in some other thread in this forum about how X360 would not be able to render 1080p games natively because of the tiling required. Something about how you can't fit two frames in the eDRAM because one 1080p image = 8MB. I looked everywhere and couldn't find it.
Something, somewhere, by somebody, was horribly misinterpreted. One, a 1080p image is larger than 8MiB. It's 1920pixels * 1080pixels * (32b color + 32b Z/stencil), which gives you ~15.82MiB. Two, 720p with no AA requires ~7MiB, which means that with either 2xAA or 4xAA, you need either two or three tiles (14MiB, 28MiB). There are numerous games that use that resolution with either of those AA values, and they require tiling. Other games support other odd resolutions, with or without AA, and some of them will require tiling. All of these work, and tiling doesn't break the output. That would be crazy, inane, and ultimately completely broken.
So, Tiling incurrs no problems regarding 1080p that it doesn't already regarding any framebuffer that exceeds 10MiB.
What you may have heard is that 1080p w/ 4xAA is out of the question, since it would require 7 tiles, and might have a pretty significant performance hit, or something along those lines.
Edit: Bleh, couldn't you have waited 7 more minutes to post that?
Also, I don't know how much mystery is still involved here, that can be applied generally to every case. Redundant transforms will cost so much , and other methods will require so much memory, bandwidth, etc. And all of that is definitely limited to a case-by-case analysis (frame-by-frame even...). Most of the stuff from Microsoft has been in the way of making things easier (for example, they've added certain additions to the compiler so that Z pre-pass can remove unnecessary instructions and the output between the Pre and normal passes match such that there's no Z fighting issues.
Edit 2: To hell with editing.