Like many other devs, I jumped on 3.0 as soon as it was launched, not so much for testing my own apps but for trying out the new features. Today I finally got up the nerve to downgrade to 2.2.1 and GOOD LORD. What a difference!!! It's amazing how fast 2.2.1 seems after using 3.0 for less than a week. I just hope they optimize the heck out of it before the official launch, or there are going to be LOTS of angry iPhone owners.