Having just returned from PMI with Ryanair, there were posters all over the airport stating that you could take a duty free bag on board as extra to your normal hand luggage. However on closer inspection there was a star at the end of it and at the bottom of the poster it stated that this was subject to the airline and to check with them first.
On another note, I have to say that I was pleasantly surprised by Ryanair. I had always been one of those people who insisted they would never fly with them. Now if the price was right, I would have no problem with them. Only observation - make sure you follow their rules and you will be fine.