Gary Price from ResourceShelf wonders if this is one of the larger promo ads ever seen in a drop down. I remember that Google displayed a similar message when Google Instant was launched: "Welcome to Google Instant. Feelings of euphoria and weightlessness are normal. Do not be alarmed."
I wouldn't be surprised to see that Google starts to show AdWords ads below the suggestions, a feature that has already been tested in Google Suggest.
{ thank you, Gary Price. }