Actually that's what Google has done with Courgette: http://www.chromium.org/developers/design-documents/software-updates-courgette http://www.chromium.org/deve

Actually that's what Google has done with Courgette: http://www.chromium.org/developers/design-documents/software-updates-courgette http://www.chromium.org/developers/design-documents/software... > Courgette transforms the input into an alternate form where binary diffing is more effective, does the differential compression in the transformed space, and inverts the transform to get the patched output in the original format. With careful choice of the alternate format we can get substantially smaller updates.