Would be nice to have the following feature set;
1. Preview of Before & After.
2. Set a different output folder/name, not touching the originals until.
3. Send/Share output - take the original and optimize it before sharing it in email/bluetooth/facebook...
Also time stamp is quite a big issue.
If you can't preserve modified file, make sure that you keep the EXIF fields so that it could be fixed according to that.