Here's Palin's mission, as reported by the AP:

Palin's unit is believed to be headed to Diyala, among the most dangerous of Iraq's 18 provinces.

Pvt. 1st Class Palin is being sent to Iraq with the Stryker Brigade Combat Team of the 25th Infantry Division. Palin, 19, will be deployed to northern Iraq and will be primarily tasked with protecting and helping transport the deputy commander of his unit, Lt. Col. Michael W. Smith. His position is one of dismounted infantryman.

"Republicans always seem to imply that Democrats are somehow unpatriotic or want to be easy on the terrorists," said James Pfiffner, a professor at George Mason University's School of Public Policy. "But I think that Biden's son demonstrates that you can disagree with a policy and still support doing your duty."

Beau Biden, who is Delaware's attorney general, is a captain in the Delaware National Guard and will work as a military lawyer in Iraq.

Although Biden's tour could be cut short, too:

Beau's deployment raises an interesting question: What will become of Biden's Senate seat if he gets the veep nods and Obama wins the election? Delaware political observers (yes, they do exist) have long presumed that Beau hoped to succeed his father.

The senator, who is seeking a seventh term this year, may remain on the November Senate ballot, according to state election law. If Biden wins both races, he can take the Senate oath and then resign. The Democratic governor, Ruth Ann Minner, would then appoint a replacement who would serve until the next general election in 2010.

The law is unclear, however, as to whether Beau Biden could be named while serving in Iraq.