Aikido has been used to bring people from communities in conflict together - in other regions. I thinking particularly of Aiki Extensions "Training Across Borders" event in Cyprus and the Salaam Shalom Aikido project between Israelis and Palestinians.
Re Ireland - I don't think aikido has ever been done with a stated "bi-communal" intent there, but this has happened naturally in some cases I believe. My being English was not a major issue while training in the Irish Republic - though I suspect it was to a minority.
I'm also interested to hear views and experiences of those in the North on this subject. Re Irish politics/troubles in general - I don't want to say too much as I'm no expert. The general view is that it's better than it was but is still far from perfect.
Views from the States on the subject are often odd in my experience - Jeanne - I feel happy that you are looking for other sources of info than Hollywood that's for sure!