Si, que si has aceptado que wordpress muestre adsense en tu blog. Mira
http://wordpress.com/features/ la ultima "feature":
Cita: Advertising
To support the service we may occasionally show Google text ads on your blog, however we do this very rarely. In the future you’ll be able to purchase an upgrade to either turn the ads off or show your own ads and make money from your blog.
Es que hay que leer los contratos.