There's already a similar post about this, but I would like to take it just a bit further:
While editing a question I do not believe there is a "Someone Edited This Question" banner. At times this can cause problems as multiple people come in, see a question that needs a bit of work, click that "edit" button and do their stuff, all clicking "Save edit" on their way out.
This has happened on this question where 3 distinct people have all tried to effectively do the same work, at the same time and ended up trampling all over each other and potentially causing aggravation for the question asker as it seems that everyone has pounced on their answer to "make it right." I don't know how often this does actually happen, but it seems like something that is likely to happen more often as the user-base grows.
Is it possible to have a banner bar similar to the "New Answers Posted" bar for when questions (or answers) get edited? Seeing this bar would make people stop their potential edits and save time and effort on work that someone may have already just done.
Or, as an alternative, an intermediate page before reloading the question that says "Someone else edited this question in the last 5/10/X minutes, are you sure you want to post this?" It could even be useful to show you the diff between your edit and the other editor.
It may be that this banner is already in place, but due to the short time scales involved between edit that it simply was not seen during the edits on the linked question as they were posted very close together.