Upon testing Sketches on firmware 1.1.3, we have detected some systems with the wrong permissions assigned to the Camera Roll album where photos are automatically stored, effectively making it impossible to save photos from either Sketches or iPhone's own Camera app.
This is probably due to some glitch in the jailbreak process, specially if you followed one of the initial 1.1.3 jailbreak guides.
To solve this issue, you have to ssh into your phone, then enter the following command:
Note you have to enter the text as a single line, copying everything that comes after the prompt sign (# )