Well basically, the mod adds a new row to the database called "slug".
This slug row contains a "url friendly" version of the title.
Image Title: My Sample Image
Image Slug: my-sample-image
Then by patching a few files in Pixelpost, adding some new template tags, and using a little mod_rewrite, one can have urls like this:
It can be ported to any version of Pixelpost, but I personally will only have it released for the old v1.5 & the soon to be v1.7.