'image/pjpeg' should be treated as an image by Web Inspector.
It's not exactly a "real" MIME type, but it's in use, and it's an image: http://cdn1.sbnation.com/entry_photo_images/7058731/annual_report_art_large_medium.jpg was on The Verge this morning. *shrug* Dunno if it's worth fixing, but it's a trivial patch.
Created attachment 169916 [details] Patch
CCing the Inspector list. Sorry, should have created this bug via the template.
Comment on attachment 169916 [details] Patch Clearing flags on attachment: 169916 Committed r132130: <http://trac.webkit.org/changeset/132130>
All reviewed patches have been landed. Closing bug.