There are several restaurants at the conference hotel, the City West Hotel: The Hibernian Bistro seems to have a few vegetarian dishes and a vegetarian pizza. The pizza (without cheese) might be vegan, depending on what they have in the dough.
Note, though, that these vegetarian options are only served from the evening menu, starting at 14:00, as far as I understand.
Lemongrass, also at the hotel, is an asian restaurant with several vegetarian dishes, some which might be vegan. It's not clear to me if they serve the entire menu for lunch.
I have contacted Deirdre O'Callaghan, docallaghan at the domain citywesthotel.com, and asked her if any of the dishes at any of the restaurants at City West are vegan. She has forwarded my mail to the head chef, but so far I have not received any reply from the chef.
I found the site Vegans are from Mars useful. There is a specific guide for Ireland and Dublin.
Happy Cow also have several listings for Dublin.
Among the most interesting restaurants are:
Note also that the bus stop for bus 69 to Saggart and Rathcoole, which passes both Green Isle Hotel, where I live, and the City West Hotel, where the conference is held, is very close. You can find the bus stop on Aston Quay.
Down the hotel drive and hang a right, and keep walking past the church you will find the village of Saggart.
The village of Saggart is a ten minute walk from the CityWest Hotel. There is a SPAR grocery store there.
There are several grocery stores in the village of Rathcoole, a somewhat longer walk from Citywest hotel. There is, for instance, a Tesco Express where I found mixed nuts, some soy products and pot noodles that appeared to be vegan.
Mary Barnes said that "both Dunne's and Mark's and Spencer have food stores in the basement floors - salads, veggies, houmous, fruits, veggies, etc. - many in individual servings".
In Dublin city, I also noticed many SPAR supermarkets.
As you probably know Guiness is unfortunately not vegan. All beer from the Guinesss brewery use isinglass, a fish product, to fine their beer as do many other beers in the anglo-saxon beer tradition.
According to Geraint Bevan's amazing beer list beer from the Dublin Brewing Company are vegan. These are:
Other than that, I will keep to beer I know is vegan. For example, it seems Heiniken and Carlsberg can be found everywhere.
If anyone has more information, please share! Mail me at mc at the domain stickybit.se. NOTE! New e-mail address. My hack.org address is currently broken. Send mail to me at work.