Google has announced that they are going to discontinue Google Toolbar for Mozilla Firefox 5.0 and newer versions. That's true that many Google toolbar features like searchbox, spell check, etc are built into Firefox but what about other useful features like Page translation, Auto-fill, Page sharing, Gmail notifications, etc?
The Official Announcement:
"First of all, we'd like to thank all of our loyal users of Google Toolbar for Firefox. We deeply appreciate all of the feedback over the years that helped to make the product so useful. As we all know, over the past few years, there has been a tremendous amount of innovation in the browser space.
For Firefox users, many features that were once offered by Google Toolbar for Firefox are now already built right into the browser. 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."