The place that comes to my mind is The Hollies in West Cork. http://thehollies.ie/ Thomas and Rike are two German friends of mine who live there and were among the first families to start it up.
Here's a link page to other sites around Ireland that may be of interest as well. http://www.permaculture.ie/links.html I did a Permaculture course at Cloughjordan Eco-village last year and loved it, worth a visit, but possibly best done in conjunction with a course or work of some sort to get an easy introduction to the village there.
Thank you so much Feidhlim! Both of those links are fantastic. The Hollies looks really cool. Some pretty neat workshops there! I might get to check out the natural building one, which would be awesome!
I have also heard that some of the castles have some pretty great gardens - thoughts?
Yes, there are excellent gardens around the country too. I'm not sure if you know the name Myrtle Allen of Ballymaloe House in Co. Cork, but she was pushing the good local food agenda before Permaculture was ever written down. She's also my grandmother. Well, the Ballymaloe Cookery School (2km from Ballymaloe House) now carries the main educational flag - selling the message of Slow Food, Organic, Fresh and Local, Rare Breeds etc. If you're looking for gardens, theirs is excellent. http://www.cookingisfun.ie/gardens/our-gardens