With a new blog, I found all goes well using utf-8 and the standard language files (thanks, Xavier, for all your work). But updating is a very different question. See this thread :
https://www.ads-software.com/support/index.php?action=vthread&forum=10&topic=7372&page=0
Also, none of my hosts (in France) were offering utf-8 as an option in PHPMyAdmin, so the only choice is to use ISO-8859-1. This implies intervening directly in the database (to get rid of garbled caracters generated in text fields).
I’ve given up on several plugins, functionning incorrectly I’ve assumed, because of the different caracter set.
The RSS feeds, which worked perfectly under 1.0.2, now contain incorrect or junk caracters. I’ve found no way to correct this and I’ll say no more as I don’t wish to annoy regular contributors to this forum.
Some words seem to escape translation. In the admin screens, I still have “Activate” and “Deactivate” for example.
Obviously, with plugins, the added menu items do not translate and can’t be found in po or mo files. So each plugin must be translated directly in the code by mugs like me who don’t have a clue about PHP.
It would be great if WordPress was truly international!
If I can do my bit, let me know.