Would love to join you guys! All depends on timing of course, but only on one condition -- I don't want my stuff next to Peter's IR prints or liths or no one will look at mine!! Definitely good stuff there for an exhibition!
You guys should also look at Sirius Art Gallery in Cobh, since they do a lot of photo exhibits, it's a GREAT space, charming area of the country, and right next to Cork, anyway. That gives you two good possible options with the Public Museum. Also in Dublin, be sure to talk to the Photography Gallery in Temple Bar as they are another outstanding venue, although getting booked there can take awhile. DCU and DIT in Dublin are other possible venues and DIT, especially, has an interest in promoting photography and you'll get plenty of exposure to college students and the "next generation" of shooters. Finally, the University of Limerick also has some great exhibition space and they have done photo shows in the past.
There are plenty of good venues in Ireland, so you might even think about taking the show to a couple of cities to maximize your exposure.