Has this one been posted somewhere? If so, I can't find it.
Former google preview:
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.4 (KHTML, like Gecko; Google Web Preview) Chrome/22.0.1229 Safari/537.4
latest google preview (differences highlighted):
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko; Google Web Preview) Chrome/27.0.1453 Safari/537.36
As always, that's Preview's own UA, not the human visitor.
Source: 66.249.81.72. The X-Forwarded-For header (google sends one, other previews generally don't) agreed with an immediately preceding image search.
:: now off to fine-tune log-processing script ::