Recent revelations about the trilinear filtering techniques ATI has used in its more recent graphics chips, including the X800 series, have been something of a shock. The reason it came as a shock isn't because we've now learned that ATI is using an adaptive algorithm to reduce its graphics workload. Such algorithms make sense, done properly, so they don't harm image quality. Indeed, the essence of graphics is creating an illusion as effectively as possible, and shortcuts are big part of that enterprise.
The shock comes because ATI has consistently touted its own texture filtering techniques as superior to the competition's, talking down the so-called "brilinear" filtering algorithim used by NVIDIA and encouraging use of tools for IQ analysis that don't show the effects of ATI's method.