If you apply at the Garda National Immigration Bureau in Dublin, you can get it immediately if you pay by credit card (the whole thing inclusive of queueing and waiting took approx. an hour).
If you apply outside of Dublin, you need to apply at your local Garda station. Then it typically take up to a week to get.
The cost is €150 and it is a laminated ID card with chip that now (since late last year) carries both your photo and fingerprints.
See
http://www.citizens...ea-nationals-in-ireland 
