It's no surprise. Apple has dropped prices on the iPhone 3GS as everyone eagerly anticipates the new Apple iPhone 4. (too bad it's not 4G)
So, if you're looking for a good deal on an Apple iPhone, it may be a good time to buy if you don't need all the latest and greatest features found on the iPhone 4. If it were me, I'd wait for the iPhone 4. Then again, I'm not a medical student or resident anymore, so I have a bit more in my bank account compared to those days.
If the iPhone 4 came on the Verizon Wireless network, my wife (a family physician) would definitely get it. I'd probably get it too. For now, we'll just have to settle for the Android, BlackBerry, webOS, and Windows Phones on the Verizon network.