A word of caution for those who make their profiles public. Most people simply append their gmail handle for these profiles. For example, JohnSmith@gmail.com would use the profile www.google.com/profiles/johnsmith.
It becomes incredibly easy for spammers to pull these handles from public searches, add an '@gmail.com' and spam them.
Ooops, too late. Got rushed by a blog article somewhere: "Hurry, Hurry, get your google profile handle now, or else ... someone else will take it!" So I did.
Nice lesson for all marketers - scaring users works :)
It's pretty ridiculously easy to use that spamming technique now -- just scrape usernames from public fora, and try them on the big free email hosts.
If you add a really naive email hashing scheme to your profile pages, the spammer doesn't even have to send the email to see if it's valid!: http://www.cs.brown.edu/~cce/microid/
It becomes incredibly easy for spammers to pull these handles from public searches, add an '@gmail.com' and spam them.