Rumours say that Google is experimenting with a new layout. Among other things, there’s a column on the left side that probably shows the relevancy of the search results in different searches (News, Images, Groups, etc.)

You can download the beta of the new version of Google Toolbar at
http://www.google.com/tools/toolbar/T4/index.html.
Information about the new features is available at
http://www.google.com/support/toolbar/bin/static.py?page=features.html&v=4.
What I find exciting about this new version is the Button Gallery where you can add new buttons to your Google toolbar:
http://www.google.com/tools/toolbar/buttons/gallery.
The API on creating new buttons:
http://www.google.com/tools/toolbar/buttons/apis/howto_guide.html