In 2012 there were 32.1 people available for work for each vacancy. Though there are some shortages for specific skills (Forfás has recently released a report on the issue), the main cause of unemployment is not a lack of people willing to work, but simply a lack of jobs.
In contrast, in Germany there are only 2.2 unemployed persons per vacancy, showing that in Germany unemployment is mainly due to people being genuinely 'between jobs', which is normal in a health economy.
More information on vacancies can be seen in indicator 2.6 of the latest NERI Quarterly Economic Facts.