J.D.
Ahh, the terrible twos. So what is it that starts around two that drives moms crazy? Independence! At this point, our peanut have learned the basics such as walking, eating, and so on. They've learned they aren't actually a PART of mommy and can do things on their own. So they want to try things on their own.
I think it scares then and excites them at the same time. Plus they have also discovered that they can express emotion (ie, screaming, whining, showing anger, frustration, and so on). However, they don't really know yet how to control those emotions. They haven't learned that part yet.
My son is in full force at four, and my daughter has JUST hit the terrible twos. They are handling it differently, but it doesn't mean it's driving me nuts.
Just hang tight, take some deep breathes and remember, it's ok for YOU to have time outs too (for your own sanity! lol...)
Also remember, be consistent with your discipline and love. :)
~J.