[Tim Wood]

This looks fine at a glance. One note though -- this API will be changing slightly in the next source release (which I started working on preparing today...). The change is pretty minor, but OUIDocumentPreview now does the CGImageRef->JPEG compression and the file I/O on a background queue to reduce the time spent blocking the main thread. This helps reduce stuttering when scrolling in the document picker while previews are being generated.