One Webmaster saw the special Googlebot-Mobile show up in his log files and posted a thread about it at Google Webmaster Help. He said:
I know Mr. John Mueller once said on twitter: Googlebot-Mobile doesn't crawl as iPhone(as far as he knows).
But I found a log like this: Mozilla/5.0 (iPhone; U; CPU iPhone OS) (compatible; Googlebot-Mobile/2.1; +http://www.google.com/bot.html")
Is there anyone who has ever seen it before? Is this a real Googlebot-Mobile?
JohnMu from Google confirmed that this can very well be a real Googlebot. John said:
We're constantly working on expanding our systems and run numerous experiments over time. That looks like an experiment which we mostly did a while back. At the moment, it's not something that we're generally using when crawling, though I wouldn't be surprised to see that or other mobile user-agents in the future as further experiments.
But as we mentioned yesterday in our Google on Mobile SEO, don't treat Googlebot-Mobile special when it comes to iPhone templates. John explained:
As with other mobile user-agents, we recommend not treating these in a special way, and instead just showing the content in the way that you would normally show users with those user-agents.
So technically, if you are serving up a special iPhone template based on an iPhone useragent, this Googlebot should get the same template.
This may be signs of new things to come, where Google can detect not just old traditional mobile web pages but also smartphone specific templates. Might come in handy in the future.
Forum discussion at Google Webmaster Help.