I'm talking about surfaces too large to be environment-mapped (eg mirrors that span the length of an entire corridor wall).
Right off the bat it seems handling concave surfaces with minor curvature might be accomplished by the simple case of using flat mirroring + rendering to an FBO and manipulating texture coordinates to distort the mirrored image (the mirror edges would still not line up - which in turn wouldn't be too big of an issue if the mirror edges didn't touch any of the mirrored surfaces). Concave and uneven surfaces get far more complex pretty quickly, though.
An alternative would be to curve the geometry when rendering the mirrored image, but I would assume the actual implementation would be far more complex than theory in this case.
Has anyone done research into this?