My 2007 property taxes are theoretically due Dec 31, 2007. However, it isn't considered late if you pay half in April 2008 and the other half in July 2008. Heck, most escrow accounts just automatically pay it in 2008 in two halves.
Here is a nice trick for those people who have cheaper houses or low interest rates (ie those of us who's itemized deductions barely beat the standard deduction on income taxes). Pay your 2006 taxes in 2007, then pay your 2007 taxes in 2007. You now double the property tax deduction in 2007 and get a big tax cut. Then in 2008 don't pay any real estate taxes (delay it until 2009). In 2008, just take the standard deduction. Sure, you'll pay a bit more tax in 2008 because you didn't itemize deductions, but the added tax will be minisucle compared to the 2007 tax savings because the standard deduction is near your itemized deduction amount. Rinse and repeat. Every other year, get a massive tax savings, every other year pay a tiny amount more in tax. Overall, you come out a big winner.
This only works if states let you pay late penalty free like mine does.