@JTT,
The Democratic party has made it very clear that Sarah Palin's daughter is off-limit including a promise from Obama to fire anyone who brings it up.
The Obama campaign is about issues... Palin's background, beliefs, her grasp of important issues and her policies are all fair game.
Palin is a skilled politician with a record. Her acceptance of ear-marks, the fact she was for the bridge to nowhere (before she was against it) and the untruths she is telling are all fair and relevant to how she is going to perfom as vice president or president.
Palin's family is clearly off limits. Palin's character, history and beliefs are fair and relevant.
The democratic party should go after her in a way that is fair and tough. All indications are that they are doing just that.