Nope you'll pay tax here, it would be a strange world where residents could avoid tax (live here, pay tax here). I believe the US taxes all her citizens so you will have to pay US taxes as well, though you will get full credit for Irish taxes paid and they will be higher than the US so you'll likely not have any additional liability. You'll just have to file nice and simple US tax returns every year.
Have a look at the guidance:
Thank you for the reply. I copied the Taxation agreement below from that site. The last paragraph is what leads me to believe differently. Am I interpreting it wrong?
Double Taxation Agreements
Double Taxation Agreements generally make a distinction between pensions payable by governments to former employees and pensions payable by private employers. There are some variations between the agreements and not all agreements make this distinction and they vary in other ways so you would need to check how exactly you are affected.
Most of them provide that pensions for non-governmental employees are taxed in the country of residence. So, if you are living in Ireland and getting an occupational pension from another country, you should generally receive it gross and then pay Irish tax on it.
The opposite is the case for pensions for former Government employees - generally they are taxable only in the country where they are paid. So, if you are a former employee of the US government now living in Ireland, you pay tax on your occupational pension in the USA only. In some cases, this applies to pensions from local authorities or other political sub-divisions - again, the particular agreement needs to be checked.