Not literally, of course, as no one since Fionn mac Cumhail has left the island on foot. Most people fly. While reliable and timely data on migration are hard to get, we do know how many people fly out of country, and how many fly in. This data can be had from the CSO for every month since January 2006. Unfortunately, the data are released with a six-month delay (courtesy of Dublin Airport Authority). They are instructive nonetheless.
Between Jan 2006 and Oct 2008, 30,282 more people arrived at one of the seven airports than left. This trend has reversed however. While 35,453 entered the Republic of Ireland between Jan 06 and Oct 06, and 72,936 between Nov 06 and Oct 07, 78,106 people left between Nov 07 and Oct 08.
That is, eighty thousand people took a one-way flight, before the scale of the recession was clear.
Of those 78,106 people, 58,980 left for Great Britain, 11,018 for Germany, 6,750 for Poland, 6,409 for the Czech Republic, and 4,161 for the Baltic countries. Between Nov 07 and Oct 08, 4,164 people came from Italy, 3,966 from France, and 2,456 from Hungary.