It would be of benefit to inlcude a box of accents and other special characters
on the upload page, similar to that at the bottom of edit pages.
I'm not a developer and so quite likely to be wrong about this, but from what I
can tell the box on the edit page is produced from the same MediaWiki page that
displays the copyright warning. The copyright warning on the upload page is
produced from a different MediaWiki page and so the accents box does not appear.
Adding it to the upload page below the "all files need to have a free license"
box would be simple for any admin to do. However, IMHO at least, it would better
to locate it below the description box, like on edit pages.
There is currently no MediaWiki page that I can see that adds anything to this
part of the page, and so a new one is probably needed - perhaps [[MediaWiki:Char
Insert]] or [[MediaWiki:Accent box]]. It would make sense to then put this box
on the edit pages as well (to keep the available symbols the same and in the
same order) and remove them from the copyright warning box - where they are
somewhat of an illiogical fit.
See [http://commons.wikimedia.org/wiki/Commons:Village_pump#Proposal: Special
signs in the upload form] for a discussion on this.