Googled this last week, the most recent news report suggests end of 2009 - google 'ikea dublin'; and you will see the report (i think its from herald.ie).
met someone at a party a few months ago who works for Ikea dublin and they said that it will be ready to go early this year (they said february) but the condition of the planning permission was that the M50- upgrade had to be ready before they could open. (apparently this is on time for November 2009)
Ikea do have cheeky signs up saying that if you cant wait that their nearest chop is 170Km away in Belfast!
anon473