Ironically, a related document with a 2010 (c) date listing their "crawlers" is conflicting...
Appendix: Google's website crawlers
Googlebot-News (née Feedfetcher?)
"Google also uses some other user-agents, not listed here, to fetch content in real time in response to a user's action." (That sounds like the troublesome new Google Web Preview
(in no particular order)
Feedfetcher-Google; (+http://www.google.com/feedfetcher.html; [...etc.]
Google Web Preview
Google Wireless Transcoder
Google Keyword Generator
Any UA... "(via translate.google.com)"
The Appendix is referenced in G's robots.txt docs rehash and refers to G's listed agents as "crawlers." That could be a doublespeakish way of saying the list-AWOL UAs ignore robots.txt. Because they do.