Hmm works on the iPhone 4, but I don't know if the 3GS is supported. Even on the iPhone 4, only pictures on the camera roll (or saved pictures) are imported. You can't transfer albums that were synced with iTunes this way.
An alternate way to transfer photos from the iPhone to iPad is PhotoSync. It's a universal app, so you can buy it once and put it on both devices. It will transfer via wi-fi or bluetooth.