I don't think you know what you're talking about. The FF toolbar (and any other PR-related extension) pulls data from a Google server and displays it. The only thing the extension API has to do with this process is displaying what data is provided. If the data provided by Google differs from what is displayed it is the extension's programmer who caused it.
The actual answer to the above question is that there may be multiple servers providing PR to the IE toolbar, FF toolbar, and various geographic locations. There has been a PR update recently any users may experience variations. The "unauthorized" PR tools and extensions that exist might be using "old" servers or code.
Often the SERPs and other data provided by the Google API differs from what is seen on most other data centers.