In 2.5x, when you use ‘UV->Project from View’ from a camera view, it attempts to scale the projected UVs according to the camera image boundaries, rather than those of the 3D viewport (as 2.49 did). This is a Good Idea. Unfortunately, it doesn’t quite seem to work.
Here (from 2.57) is the view of the default cube through the default camera, with a generated grid as background image:
Note that the size of the generated image has been chosen to have exactly the same 16:9 ratio as the camera; the grid squares are square in the camera view.
And here is the result of projecting the UVs from that view:
The result is shrunk in the X direction, by (surprise, surprise) a ratio of 9/16.
Is this a bug, or is there some setting somewhere that I can tweak (once, not every time I project) to make it work right?
(No, playing with aspect ratios does not help; besides, those are only supposed to be needed for non-square pixels.)