I know what you're thinking. You wish you had a camera app that allows you to easily throw pics up on Facebook or Twitter from your iPhone with no fuss. Great news! PicBounce (Free in the App store) by Clixtr is the app you've been looking for. If you're always sending pics to Facebook and Twitter to keep your friends and family up-to-date, you will love this app. I have never seen an easier app to satisfy your need for constant Facebook-pic-uploading.
PicBounce is a camera. Tap the app, and you'll feel like you're opening your camera app. The only real difference between this app and your camera is that everything in this app is designed for quickly bouncing pics right to Facebook and Twitter in one fell swoop. When you first snap a pic and tap Upload, you'll have to get the sign-in process out of the way, but don't worry – you merely have to sign in to your Facebook or Twitter or both, no third party involved. After you've done that, enter the caption you'd like on the pic, and upload it!
(Wow, that is so easy!) I know.
After you're signed in and all that is taken care of, the upload process is as easy as a tap, every time you take a pic. When you're on the camera interface, the bottom left-hand corner contains the button for your photo albums. Here you can grab pics that you've previously taken, and load them up in the way previously described. The bottom right-hand corner has your "history" page, where you can view all the pics you've uploaded and the captions you've put on each of them.
The only thing I can think of to improve the functionality of this app would be to allow for MMS-ing pics from the photo album in PicBounce, rather than having to jump around to different cameras on your phone. However, this app does what it says, so I'm not complaining. Download, and give it a try.