DropPhox (US$1.99) from DaVinciWare Inc. is a little gem that everyone using an iOS device with a camera (and Dropbox) should go out and buy. This app allows you to snap pictures or videos, and have them wirelessly transfer to your Dropbox account via either 3G or Wi-Fi. We love Dropbox around here and use it for just about everything.
The first thing you'll do is link DropPhox to your Dropbox account. By default, a folder will be created in Dropbox -- named, not surprisingly, DropPhox, but you can change it if you'd like. Once you take a picture, if there is a connection, the pictures or videos will transfer. If no connection exists, transfer will be put on hold and resume as soon as DropPhox detects one. That's it. It works seamlessly, perfectly and every time.
There are a number of things you can set either in DropPhox, or in the Settings app to tailor things to your liking. The first one is the size of the image. I don't have an iPhone 4, but on my 3GS, I can choose between, original, 1200x600, 960x1280 or 600x800. This is important, since an original resolution shot can be over 3 MB large, and sometimes you don't need the higher resolution image in Dropbox. In the Settings app, there are also options to enable or disable saving to your camera roll, choose a date format (all the shots are named starting with the date, so this may come in handy) and a few other settings. In the DropPhox app, you can provide the needed Dropbox settings, select a saving directory and turn Geotagging on or off.