I'm loving this app called CameraSync. You run it and it starts uploading your Camera Roll to your Dropbox. Once it starts uploading you can get out of the app and it will continue to upload in the backround and even give you a push notification when it's done. It's a Universal Binary so it works on the iPad too. It cost $1.99
CameraSync for iPhone, iPod touch, and iPad on the iTunes App Store
CameraSync for iPhone, iPod touch, and iPad on the iTunes App Store