I read some articles about Satoshi's history and stumbled upon this one:
No one knows what Satoshi is up to, but one of the last emails he sent to a software developer, dated April 23 2011, said “I’ve moved on to other things. It’s in good hands with Gavin and everyone.”
This sentence of Satoshi is quoted many times in the web, but I can't find a source who published it or to which developer it was send. I know there are archives of Satoshi's mails but I didn't find this statement in any of them.
Does anybody have further information about it?