'Global Entry' is a U.S. Customs and Border Protection (CBP) program that allows expedited clearance for pre-approved, low-risk US travellers upon arrival in the United States. While the goal of Global Entry is to speed travellers through the process, no traveller is guaranteed expedited screening and members may be selected for further examination when entering the United States.
I understand that earlier this month this programme was extended to UK citizens with US citizens being given access to the UK's equivalent 'registered traveller' programme. UK citizens still need to apply and go through various steps before being able to avail of the US programme.
Ireland has no equivalent programme for frequent visitors to this country and consequently there are currently no plans to open negotiations with the United States for access to the 'Global Entry' programme. However both Shannon and Dublin airports have arrangements in place for US flights which allow passengers to undergo US CBP clearance before leaving Ireland, thereby greatly expediting their arrival procedures at US airports.