I got email late today saying that my Firefox extension is being retained in the sandbox (staying in development) pending user reviews. So if you are so inclined, I encourage you to post a user review. As an incentive, by downloading the extension, you'll be able to view the source code for a simple Firefox extention (it's got an .xpi extension, but it's really just a zip file). So if you ever had the urge to write an extension, this might be a good place to start.
If you'd like to post a review, you can either sign up for a developer account and post the review that way (here are a few notes about that), or you can write an external review (I assume that comments to this blog would work for that). If you sign up for a developer account, you'll be able to see the extension's sandbox page. Or you can visit the project home page.
To review the extension, go to about:config and search for the network.dnsCacheEntries item. You should be able to see this item's value change between 0 and 1 when toggling the extension menu item. If you run your own DNS or aren't afraid to fiddle with your hosts file, you might be able to observe the browser caching (or not caching) IP addresses.
I don't have access to a Mac, so a review of the extension by a Mac user might be useful. And the more details your review provides, the more likely it is to have an impact on the evaluation process.