Its a graduated labs thing called Don't forget bob Here is the original press release http://gmailblog.blogspot.com/2009/04/new-in-labs-suggest-more-recipients.

Its a graduated labs thing called Don't forget bob Here is the original press release http://gmailblog.blogspot.com/2009/04/new-in-labs-suggest-more-recipients.html http://gmailblog.blogspot.com/2009/04/new-in-labs-suggest-mo... It uses your own history, and no one elses. So nope - no security issue. Just connivence.