From their website (buried in the "new routes for Dublin release October 18, i won't post a link as I'm not sure if it's allowed) :
Ryanair also announced today a new online check-in and priority boarding service enhancement that will allow all passengers to enjoy online check-in / priority boarding for just £2/€3 per flight from 1st November. This service improvement will extend the option of priority boarding to all passengers and not just those travelling without checked in bags as was previously the case.
Passengers travelling with checked in luggage will (from 1st November) be able to enjoy priority boarding at departure gates for £2/€3 per flight. These passengers will then be entitled to board the aircraft first and choose their seats. This will be particularly advantageous for families and groups who wish to travel together.
Those travelling with hand luggage only will also have the option to enjoy the double benefit of bypassing airport check-in queues and priority boarding at the departure gate by checking in on line for just £2/€3 per flight.
From 1st November, families with children will no longer be pre-boarded however they will have the option of online check-in and priority boarding if travelling without checked in luggage or priority boarding purchased at the airport if travelling with checked in bags.