Hi Martin:
Eire is kind of complicated to map. It's not a Garmin issue - Garmin doesn't make maps, they buy their cartography from Navteq. Anyway, the story is this: It seems that the Government of Ireland has no electronic data that shows the roads in the country... and no plans to produce any. This means that the cartography companies (Navteq, TeleAtlas, et al) will have to create the vector mapping data themselves, which they are slowly doing. But, obviously, they are concentrating their efforts on the populated bits of the country (Dublin, for example), and it might be a long time - years and years - before the whole country is mapped.
By comparison, some European countries - for example, Switzerland - had the whole country mapped in vector format, right down to the cow paths, before Navteq even came knocking on the door back in the mid 1990s. That's great so far as convenience is concerned, however, it also explains why the GPSRs are so darn expensive in Europe. In North America, the governments of Canada and the USA put the electronic vector cartography into the public domain, so it costs Navteq nothing to acquire the basic data - although they do spend a lot of money adding detail to it. In Europe, Navteq has to buy the data from all the different governments - I think about 25 different ones at last count. It doesn't come cheap - the governments charge royalties on every CD sold.
If you have a European GPSR, and want to buy the CD with the North American data, it costs about $150 or so. If you have a North American GPSR, and want to buy the European maps, it costs about $550. That's entirely due to the royalties paid to the various governments in Europe.
Michael