Earlier this week, Google announced it was killing Google Toolbar for Firefox, and would not be updating the add-on to support Firefox 5 or future versions of the open-source browser.

Mozilla shipped a month ago.

"For Firefox users, many features that were once offered by Google Toolbar for Firefox are now already built right into the browser," said Google in a Tuesday. "Therefore, while Google Toolbar for Firefox works on versions up to and including Firefox 4 only, it will not be supported on Firefox 5 and future versions."

Google Toolbar adds several features to Firefox, including syncing bookmarks to a Google account, translating foreign-language websites and sharing pages with others.

Although a Google spokeswoman today said that the company had been talking with Mozilla about the demise of the Toolbar "for some time now," the decision seemed to catch Mozilla by surprise. On Thursday, Christian Legnitto, Firefox's release manager, put out a call for a developer meeting later in the day to plan Mozilla's next moves.