The current default sorting mode is oldest to newest pictures, I’d love an option to reverse that, so I see my newest pictures first.
It would indeed be nice to have an option for sorting.
Somewhat related, I find it somewhat inconsistent that the Photo Stream sorts events and photos oldest to newest, whereas the Events sidebar lists event from newest to oldest.
Personally, it would make more sense to me if the sorting of the Photo Stream and Events sidebar were aligned.