Google Web Accelerator
From Electrical Engineering TA Handbook
When you access Wikipedia using Google Web Accelerator, the connection is routed through one of a small pool of proxy servers set up by Google. Because of persistent abuse and vandalism by some users, these proxy servers are now being indefinitely blocked from editing Wikipedia. Other innocent users may also end up "automatically blocked" as "collateral damage". This document attempts to explain why this happens and what you can do to avoid it.
What should I do if I find myself blocked?
You should disable Google Web Accelerator for this website. You do not need to uninstall the software altogether.
Go to your Google Web Accelerator toolbar, click the speedometer icon button, which brings up a menu, and select "Don't accelerate this website" (as depicted here).
If your browser does not have this toolbar, you will have to click on the Google Web Accelerator speedometer icon in your system tray and select Preferences... or visit http://127.0.0.1:9100/preferences. Once the Preferences page has loaded, add .wikipedia.org (please note the preceding fullstop/period) to your "Sites that you do not want to use Google Web Accelerator" list and click Save Preferences.
Once you have disabled Google Web Accelerator for Wikipedia, you should be able to resume editing right away. If you are still blocked for using Google Web Accelerator according to MediaWiki and you have double checked that your settings are correct you may just need to bypass or clear your web browser's cache.
Why is Google Web Accelerator blocked?
MediaWiki, the software that powers Wikipedia, identifies users either by username or by IP address. (Since unregistered users have no username, the two things are effectively the same). The IP addresses of registered users are not displayed for privacy reasons, not even to administrators, but the software still keeps track of them, and they can be viewed by people with CheckUser access.
Wikipedia's servers currently cannot distinguish one Google Web Accelerator user from another. As edits from Google no longer appear to be coming from an editor's own IP address, but from Google's own, abusive editors and vandals are using the software to conceal their true IP address from the MediaWiki software and evade blocks. The Wikimedia Foundation currently forbids users from editing Wikimedia projects through such "open proxies" under the No open proxies policy.
Since not all IP addresses utilized by Google Web Accelerator have yet been identified and blocked, other users may also end up blocked because of autoblocking, a feature of the MediaWiki software. If a registered user tries to edit Wikipedia while their username is blocked, the IP address they tried to edit from may be automatically blocked for up to 24 hours. Because edits made by a Google Web Accelerator user come from multiple proxies, a single user persistently trying to edit while blocked can cause many Google Web Accelerator proxies to be autoblocked.
An administrator blocking a registered user has no way of knowing if they're editing from Google Web Accelerator or not, since they cannot see their IP address, nor are they notified of blocks made in their name by the autoblocker (though they can search for them in the IP block list).