It looks as though Ireland is going to challenge the the EU parliament's passing of the data retention directive. It will apparently be done on procedural grounds and to defend the principle of Ireland's autonomy on justice matters.
The Commission's lawyers have already pointed out that the process has no legal basis so there is a good chance that such action on the part of the Irish government will be successful, if it is pursued to a natural conclusion in the European Court of Justice (ECJ). This all takes time, though.
The data retention vote seems, thus far, to have bypassed the attention of most of the mainstream media outlets in the UK, apart from the Guardian.