If you received payslips, then the income has been included in 2008.
It is just that he hasn't actually paid you the full net salary.
Whether or not he has paid over the tax to the Revenue is not your problem. They will chase him for the unpaid tax and PRSI.
Wait to get the P60, but in the meantine, at least you have your payslips to show the Revenue if there is any issue - guard these with your life, in case he never issues you with your P60.
Your employer must be in trouble if he can't pay you your net salary on time.