Add-on for Boost to cache images

I would like to use Boost to create a completely exportable site mirror (as detailed in the Boost Handbook at http://drupal.org/node/583264#rsync). But Boost does not cache images, only HTML, CSS, and JS.

I have already mostly completed work on a module that uses Boost's hook_boost_preprocess() hook to grab the images out of the page being cached, and then adds some lines to the generated .htaccess rules to handle the additional file types. The user can list which image file types will be cached, based on file extensions.

I would be willing to put some extra work into integrating this functionality into the main Boost module if that seemed like a good idea, or I'm happy to put it out there as its own add-on.

Any feedback?