My wife was having trouble with her iPhone 4 not uploading photos to Facebook, done all the sensible things to try and fix it, looked around the settings to work out what it could be and it turns out, if you have this problem of not being able to upload a photo to Facebook using the Facebook app, you have to make sure the Location Services is switched on.

To check this, go to:
Settings > General > Location Services
Check that Facebook button is switched from OFF to ON.

That’s it. Go back in to the Facebook App and happy uploading. Note that this issue was with version 3.3.3 of the App. Hope it helps anyone else who may have this problem