Thanks Eurello! What you suggested was not exactly what Google was asking me to do, but i did it and it looks like it worked... :-)
So next question would be: is there any way I can put on my wordpress.com blog a "Follow button" linked to my Google+ page, with the bubble showing the number of followers?
The reason why I ask is because I would like to set up a very easy-no-commitment way to follow my blog. So far all I have is the email subscriptions (which I think people don't like because they already get enough spam in their mailboxes) and the WordPress follow button, which is not friendly to non-wordpress users because it requires to open a WordPress profile and use Reader....