There is a very small gay scene in Dublin. Dublin's a small city by US standards (metro area around a million or so) and Ireland's total population is around 3 million. Ireland's public policy was very heavily influenced by the Catholic Church until 20 or so years ago. Divorce only became legal since then; abortion is still outlawed. I spent summers there as a kid, and there was absolutely no pornography or condoms -- at least not on any store shelves. I remember a visiting uncle took home to Ireland two or three Playboy magazines. The centerfolds remained nailed up inside his barn for ten years.
But back to your question, I think there are two gay bars in the Temple Bar district, but that's about it. There's almost no gay life in Ireland outside Dublin, but you may find some gay-friendly places in Cork or Galway (cities with a higher concentration of uni students).
The great thing about Ireland is that the people are extremely, genuinely friendly and outgoing. Despite that lack of gay life, you should have no problem at all in Ireland. People will gladly engage you in conversation and you'll quickly make good friends.
Oh, I can assure anyone who is interested: the "Irish curse" is completely baseless.