Ryanair know this is coming and they are gearing up for it. All EU crew that transfer now have no choice but to pay Social Security in that country (from June 28th 2012), but tax is still payable in Ireland under EU law. Those crew in EU bases currently will be safe for a maximum of ten years before the change.
For Ryanair it doesnt mean too much, for the crew it means a reduced take home pay. Will Ryanair increase wages to counteract....maybe in the long term but not dramatically.
The UK is totally unaffected (for cabin crew at least) as all UK based crew are on UK contracts as it is paying UK salaries. Flight crew I think are slightly different depending on the contract.
Wouldnt see so much of an issue in Italy. Ryanair need Italy and Italy need Ryanair, Im sure they will meet in the middle at some point on this. But as usual, the Ryanair bashers see it as "the end for Ryanair"....yawn.