E-mail Feature
I was also looking for a tweak that did that, but I didn't find any. What I ended up doing is using the E-mail feature of facebook. You are assigned a personal E-mail address and if you send pictures or videos to that address, they are published to facebook with the caption being the subject of the E-mail. I created a contact called Facebook on my iPhone with the E-mail address given to me, so I just choose pictures from the picture roll and click on Email and write Facebook on the "to" field.
This is not a tweak but an alternative that works quite well and is as fast as a tweak would be. If you find a tweak, do post it here please.