Why not add wiping Firefox's cache to Browser Wipe's capability?
For one simple reason: Firefox can be set to never cache any files onto the hard drive in the first place, so if properly configured for security, there are no cached files that need wiping to maintain privacy. Microsoft Internet Explorer cannot be set to never cache any files onto the hard drive. Microsoft Internet Explorer requires that at least 8MB of hard drive space be used for caching files.
You can set Firefox to never cache any files by doing the following:
I'd also suggest that Firefox be set to delete all cookies on exit (under the privacy tab) and that BetterPrivacy, Flashblock, Ghostery, HTTPS-Everywhere, Lightbeam and NoScript add-ons be installed and properly configured.