From the information supplied, there are three issues to look at here.
1. Domicile
Is your friend domiciled in Ireland?
If he was in the past, then he is domiciled here unless he has chosen another country as his new domicile i.e. a domicile of choice. To choose a new domicile, he must have severed all ties with Ireland and intends to reside permanently in the country he has chosen as his new domicile.
You must have a domicile and you can only have one domicile at any one time. Unless your friend has chosen a new domicile, he is still Irish domiciled.
2. Ordinary Residence
Your friend was resident in Ireland in the 2008 tax year and spent more than 30 days in Ireland in 2009. If he spent 270 days or more in Ireland in 2008 and 2009, then he is resident in Ireland for both 2008 and 2009.
3. Resident
Your friend is tax resident for 2008 and 2009.
Therefore, all your friend's worldwide income for both 2008 and 2009 is liable to Irish income tax regardless of where the income is earned and whether it is remitted to Ireland or not.
The only other option for your friend is to apply for split year residence relief in the tax year he left Ireland i.e. 2009. I am not sure if you can do this now, after the tax year is up.
Under split year residence relief, he would no longer be liable to Irish income tax on any income he earns abroad. So if he left Ireland in 2009 and does not intend to be resident in Ireland in 2010, he would not pay Irish income tax on income he earns abroad.