Invitation spam email

An interesting note titled 'New form of invitation Spam Email'

As the note says, "Even Facebook has joined on the invitation spam bandwagon.". I wonder if there are any estimates of how many invitations are being sent daily by the social networking invite features.

Interesting, this article has a reference to the one written by Paul Nikkel "Facebook reaches new lows with email invitation spam"

Which in turns has a reference to this excellent note, "Is Facebook using invitation email addresses for sign-up spam?" (with my comment at the end :) )

The question at the bottom is very similar to the one I have in my first post:

The email does have an unsubscribe link at the bottom but does it matter? If I have never given Facebook my email, I have never opted-in nor had the chance to opt-out of these Facebook marketing emails.

I read the comments on this last article and I'm just shocked. The key? The comment by Herc, July 22nd 2009 at 9:36 am:

It is now blatanntly obvuious that gmail and facebook are sharing email addresses.