Last night I was doing my nightly sweep through my inbox to make sure that I haven't missed anything important and low and behold this weird looking red mail in my inbox, BUT WAIT! It's an ad! 
Now I am one of the first to not complain about ads when it is a free service, but this is setting a alarming precedence that I don't think I care for.When I was clicking on my tabs in GMail I thought it was viewing a new labeling look for mail, YEH I WISH, because I use the crap out of some labeling in GMAIL.
It even acts as mail. You can open it and forward to other people... Ironically in the right hand of the "admail" it describes itself as:
"It's a new type of ad which you can forward to a friend, or star to save it to your inbox. If you dismiss this ad, you won't see it again."I have never noticed this before so I did some digging and turns out that this ad is based on information from my Google Account.
I have never noticed this settings page which made me speculate that is was new: https://www.google.com/settings/u/0/ads/preferences?wta=1#wta
So down and down the rabbit hole I go. I found the page that allows you to control your ads: https://www.google.com/settings/u/0/ads?wta=1.
This page was very interesting to me because if I go edit and view some of the information Google's algorithm has collected from me I can tell that it's pretty accurate. Like my interest for example.
What I can tell though that their ad setting help page has gone from this: https://support.google.com/ads/answer/2662856?hl=en
On April 5, 2013 to this: https://support.google.com/ads/answer/1634057?hl=en&ref_topic=2971788
Updated On June 27, 2013:
So that's what those blanket privacy Terms of service that we agree to while ago... lol
I don't know how many of these can fill up in GMail or how often they pop up, but I'm keeping my eye out.