According to the Google Press Center "Today we announced the latest version of Google Toolbar for Internet Explorer. The beta version is now available in US-English at http://toolbar.google.com/T5."
The new features are:
Add your favorite Google Gadgets:
"Universal Google Gadgets now work from Google Toolbar and give users access to additional tools, functionality and content right from the browser. For developers, Google Toolbar is now an additional channel to distribute gadgets, especially ones designed to interact with the websites users visit."
Fill in forms with a single click:
"Toolbar's AutoFill feature, which lets users fill out web forms with a single click using address and contact information saved with the Toolbar. This new version has better accuracy, allows users to preview the filled-in form and even maintain multiple profiles." For instance, if you are to get packages shipped to both your home and office then you can set up a different profile for each address.
Access your Toolbar from any computer:
You can now save your Toolbar settings online "and access bookmarks, custom buttons and other preferences from any Google Toolbar." If you move between two places such as home and office "or are installing Toolbar on a new computer, can retrieve all their settings instantly by signing in to their Google Account."
Clip and collect content as you browse:
"…now with Google Notebook as part of Toolbar, users can collect, organize and share more information from the web including text and images. This integration makes it easier and more efficient to do all kinds Internet research from planning a vacation to comparison shopping."
Get suggestions for broken links:
If you've mistyped a web address or if a site is down, now you won't get the usual 404 or DNS error page. Rather you "will see suggestions for top related pages. This feature is similar to the "did you mean?" function when you do a Google search."
Besides, "This new version of Google Toolbar 5 also includes full keyboard access and support for Windows accessibility API's."
You might want to watch this video about the new features by Google's product managers, Avni and Aseem.