What are some behavior problems that are typical of 3-year-olds? My little one is having new issues!?

Since my daughter turned three she has been acting a little bit more defiant ad rude (especially to Mommy). Is this a normal change for this age? It's driving me nuts, because all of a sudden she is testing me constantly and raising her voice to me. Terrible Two's had some issues but now it's different--more defiant and oppositional. Please share.