State Pension:
If you have come from a country with which Ireland has a Bilateral Social Security Agreement, your pension rights from the other country are protected when you move to Ireland. You may be able to combine your insurance records from Ireland and the appropriate country in order to qualify for a pension. It is possible to have a pension from Ireland and one or all of the other countries.

State Pension Rates 2012 (Contributory)
Max Personal rate, aged 66 - 80 €230.30 (240.30 for over 80's)
Qualified adult aged 66 and over €206.30

Non Contributory Rate 2012 (Means Tested)
Single Person €219
Qualified adult aged 66 and over €144.70

The Social Welfare and Pensions Act 2011 made a number of changes to the qualifying age for State pensions. The qualifying age will rise to 66 in 2014, 67 in 2021 and 68 in 2028.

Contributory Pension (State) :
If you reach pension age on or after 6th April 2002, you will need to have 260 paid contributions (effectively 5 years contributions but they need not be consecutive). However, if you were a voluntary contributor on or before April 6 1997, you need only have 156 paid contributions if you have a yearly average of at least 20 contributions.

If you reach pension age on or after April 6 2012, you will need to have 520 paid contributions (10 years paid contributions). In this case, not more than 260 of the 520 contributions may be voluntary contributions. However, if you were a voluntary contributor on or before April 6 1997 and you have a yearly average of 10 contributions, you may meet the requirement if you have a total of 520 contributions, but only 156 need to be compulsory paid contributions.

There were also some changes to Pension levels in Budget 2012 - that come into effect from September 2012 - see here about Pension Cuts in 2012

Occupational Pensions are not provided by all employers in Ireland. But Personal Retirement Savings Accounts (PRSAs) were introduced in Ireland in 2002. A Personal Retirement Savings Account is long-term personal retirement account designed to enable you to save for retirement in a flexible manner.
A PRSA is a contract between you and a PRSA provider in the form of an investment account. PRSAs allow you to change employment and continue to use the same PRSA. You can also switch from one PRSA to another at any time, free of charge.

Tax relief based on your age will be given by the Government for the contributions you pay into your PRSA. Employers that do not provide an occupational pension scheme for their employees are obliged to provide access to at least one Standard PRSA . Employers are required to have provided access to a PRSA to employees who are not entitled to join a pension scheme within 6 months of existing service.

PRSA Providers:
Hibernian , Eagle Star , Ark Life, Educational Building Society, Irish Life, Standard Life.

Tip: There is a " Homemaker's Scheme" run by the Department of Social and Family Affairs in Ireland that makes it easier for a homemaker to qualify for the Old Age Contributory Pension. A homemaker is defined as a person (male or female) who gives up work to take care of a child aged under 12 or an incapacitated child/adult aged 12 or over on or after 6 April 1994. More Here. Note - you have to have paid PRSI (national insurance) in Ireland for at least one week.