I read that Ryanair now allows carrying a bag of airport purchases ("duty free") in addition to one carry-on bag, but only in certain airports.
In which airports?
As far as I know Ryanair never stated that it is possible to bring on board an extra bag with the airport purchase, this is what is official.
Anyway, in my personal experience it really depends on the policy applied by the airport: I'm a frequent Ryanair passenger and I only found a single Ryanair airport not allowing carrying on board the duty free shop (Budapest airport).
In a lot of airports (for example Alghero, Pisa, Cagliari, Bergamo) loudspeakers and banners at the entrance of the shops inform the passangers that the airport security allows carrying on board an extra bag. My advice is to look for these banners once you arrive at the airport.
I KEEP TRACK HERE OF THE AIRPORTS THAT ALLOW TO CARRY ON BOARD THE DUTY FREE BAG, feel free to edit.
Allow: Alghero (AHO, 06/2013), Bergamo (BGY, 08/2012), Cagliari (CAG, 06/2013), Pisa (PSA, 07/2013), Tenerife South (TFS, 03/2013), Gran Canaria (LPA, 07/2013), Alicante (ALC, 07/2013)
Don't allow: Karlsruhe/Baden-Baden (FKB, 04/2013), Budapest (BUD, 07/2012)
At Brussels South Charleroi (Belgium) you may take one bag with purchases from the "Sky shop" after the security check, in addition to your hand bagage.
Thank you for your interest in this question.
Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).
Would you like to answer one of these unanswered questions instead?