Just an idea, don't know if I'll find time to implement it:
Long articles can get painful to edit, because you have to scroll to the section you want to work on, and always load the entire page. Some browsers also have problems with long texts. Realistically, some articles will always be in the 20-30K range. So an easy way to edit smaller portions of a large article might make sense.
We already have section markers in the text:
== foo ==
=== bar ===
It would not be very difficult to add a little [edit] link behind each section headline (should be made as non-ugly as possible), which would lead to an URL like
http://www.wikipedia.org/w/ wiki.phtml?title=Robert_Atkins&action=edit§ion=References
The resulting edit window would only contain the text from this section and subsection. Preview would also only show this text. When saved, it would be merged with the remaining text.
Edit conflicts could be handled at first like they are now: If an edit conflict occurs, the entire text - not just the section - has to be edited again. However, smarter edit conflict handling would be neat -- if someone edits text in an entirely different section, the two edits could be auto- merged.
The name of the section that is being edited could also be automatically added to the recent changes comment line, so when I edit ==External links==, the text (section: "External links") is appended to the RC comment.
One problem case would be articles with duplicate section titles. To properly reference section titles, there might therefore have to be an additional iteration parameter. Or we assume that this doesn't happen and always edit the first section of that name.
What do you think?
Regards,
Erik