Actually the scenario I referred to happened back in 2005/2006. But we will hit the 27 payrolls in 2009 because of how it falls with 2010.
And the CFO and I have been discussing it and have decided for exempt salaried individuals that we will take the annual salary and divide it by 27 rather than 26 in 2009 so that the year end 2009 salaries will be what the employer expects to pay, rather than one higher. I am sure it will make some employees mad (because their biweekly will go down about 4%), but the employer can not take the hit of an extra payroll in 2009 unfortunately. Not in this economy. In years past though they could and might have taken the hit.
In 05/06, I didn't get any negative feedback, only some questions about why their W2 for both years was first high and then low compared to their annual salary. I didn't have one person complain about the taxable consequences....or that it changed their tax bracket.
To answer your question on when you should pay if the paydate falls on the holiday, you need to check your state wage laws. Some have specific requirements. You can always do more, but not less than the state law. Our policy is to pay on the day prior, but I do know some companies (in misc states) that pay after.