You dont even need the app. If you go to photobucket.com on your iphone it brings you to a mobile site. Login and go to the bottom. There is a button to upload. This will give you an email address that you can email all your pics to, and they just show up in your library. Either way works just as well.
I really only do that if Im on the go though. Otherwise I just email the pics to myself and open them on my home comp, and upload from there. More editing options this way before I post them.
Cheers
Mark