From today's Irish Times:
AER LINGUS and Aer Arann are in advanced talks about a commercial alliance that would see them operate joint flights from provincial UK cities to Dublin and Cork. But this will not involve Aer Lingus taking an equity stake in its rival.
It is understood that Aer Arann would operate feeder services on behalf of Aer Lingus from certain UK cities to its main Irish bases at Dublin and Cork. This is a form of code sharing that is common in the airline industry.
Aer Lingus and Aer Arann discuss new alliance - The Irish Times - Wed, Jan 06, 2010