Below is a simple test I set up to try and determine if the Google tool bar sends info back to Google when a request is sent to access a web page by a browser. Browser is IE 6, Toolbar uses advanced install with PR display…The test page I used was webmasterworld.com First thing I did was to clear my cache files then take a note of now many bites had been sent in my current dial up duration. I then access webmasterworld without the toolbar loaded and take a note of the new figure that represents the bytes sent. I then go back and clear my cache. This time I load up the tool bar and take a new note of the byte reading before accessing webmasterworld again. I then take another reading of bites sent and work out the difference… I was then able to work out now many more bytes are sent with the toolbar loaded as opposed to unloaded.
Test 1 No tool bar loaded, cache cleared, access webmasterworld.com Bytes sent before 31323 Bytes sent after 33900 Total bytes sent 2577
Test 2 Tool bar loaded, cache cleared, access webmasterworld.com Bytes sent before 38452 Bytes sent after 41703 Total bytes sent 3251
Difference shows that when loading a page using the tool bar 676 bytes more are sent that loading the same page without the tool bar.
this topic was discussed many times before. google toolbar with advanced features enabled does send a request to google.com which contains the uri of the document you visit and your google id which is also present in the cookies set by google when you visit their searchpage