The Supreme Court has held that two Irish Times journalists can assert a privilege to refuse to answer questions about their sources, reversing the High Court decision in Mahon v Keena  IEHC 348 (23 October 2007). From the Irish Times breaking news website:
The Supreme Court has upheld an appeal by Irish Times editor Geraldine Kennedy and public affairs correspondent Colm Keena against a court order requiring them to answer questions from the Mahon tribunal about the source of an article about former taoiseach Bertie Ahern. …
Revised: The decision is also noted by Cian on Blurred Keys and is now avaialble as Mahon Tribunal v Keena  IESC 64 (31 July 2009); it is also here (pdf) on the Irish Times website.
See also the Belfast decision in the case of Suzanne Breen and a decision of the Supreme Court of Western Australia earlier this week, both reaching similar conclusions.