There's an
old thread on this from 2010 [webmasterworld.com], however that thread is closed.
I've had some strange correlation between a Level3 IP and Google Web Preview.
I had an earlier requests from the same Level3 IP were duplicated as part of somebody's workplace environment in which another IP's requests were the primary visitor.
I suppose the correlation could be related to the users toolbar, however the coincidence is most interesting.
8.28.16.zzz - - [24/Jul/2012:21:30:53 +0100] "GET /MyFolder/MyPage.html HTTP/1.1" 403 559 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; InfoPath.1; .NET CLR 2.0.50727; .NET CLR 1.1.4322; MS-RTC LM 8; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)"
209.85.224.95 - - [24/Jul/2012:21:30:53 +0100] "GET /SameFolder/SamePage.html HTTP/1.1" 403 559 "http://www.google.com/search" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.8 (KHTML, like Gecko; Google Web Preview) Chrome/19.0.1084.36 Safari/536.8"
8.28.16.zzz - - [24/Jul/2012:21:30:54 +0100] "GET /MyFolder/MyPage1.html HTTP/1.1" 403 559 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; InfoPath.1; .NET CLR 2.0.50727; .NET CLR 1.1.4322; MS-RTC LM 8; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)"
209.85.224.95 - - [24/Jul/2012:21:30:54 +0100] "GET /SameFolder/SamePage1.html HTTP/1.1" 403 559 "http://www.google.com/search" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.8 (KHTML, like Gecko; Google Web Preview) Chrome/19.0.1084.36 Safari/536.8"
8.28.16.zzz - - [24/Jul/2012:21:30:54 +0100] "GET /MyFolder/MyPage2.html HTTP/1.1" 403 559 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; InfoPath.1; .NET CLR 2.0.50727; .NET CLR 1.1.4322; MS-RTC LM 8; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)"
209.85.224.95 - - [24/Jul/2012:21:30:55 +0100] "GET /SameFolder/SamePage2.html HTTP/1.1" 403 559 "http://www.google.com/search" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.8 (KHTML, like Gecko; Google Web Preview) Chrome/19.0.1084.36 Safari/536.8"