For quite a while I have had a problem with the readme files that get uploaded with my plugins. Whether the plugin repository read it and used it or not seemed to be random. Which left my most popular plugin, Fun with Sidebar Tabs, without the basic information on the download page.
To try and resolve the problem I wrote and rewrote the document, downloaded ones that worked and rewrote them, tried Unix, Windows and Mac line delimiters and nothing seemed to work.
A few days ago I finally solved the problem. It was the file encoding.
I am using Aptana Studio for my development work, and it is great. But it saves text files as UTF8. When I opened my readme file in notepad and saved it as ANSI it all started to work. Simple as anything.
I wont pretend to understand it but it works.