There are still a lot of problems when converting a site from latin to UTF8.
Here a some links which describe what has to be done and how:
Unicode Theory:
http://www.joelonsoftware.com/articles/Unicode.html
cheatsheet
http://developer.loftdigital.com/blog/php-utf-8-cheatsheet
unifier
http://www.melody-soft.com/html/unifier.html
MySQL 4.1 und Zeichensätze
http://www.hosteurope.de/faq/index.php?cpid=12229
Using UTF-8 with UltraEdit
http://www.ultraedit.com/index.php?name=Forums&file=viewtopic&t=3511&highlight=unicode
PHP 6/Unicode design document
http://devzone.zend.com/content/summaries/php-unicode-design.txt
Andrei Zmievski’s presentations
http://www.gravitonic.com/talks/
Unicode Consortium reference point
http://www.unicode.org/
The ICU Library at the core of PHP 6
http://www.icu-project.org/
Joel Spolsky’s introduction to Unicode
http://www.joelonsoftware.com/articles/Unicode.html
Handling UTF-8 with PHP
http://www.phpwact.org/php/i18n/utf-8
utf-8-und-die-entity
http://blog.antikoerperchen.de/beitrag/42/utf-8-und-die-entity.html
PHP UTF-8 is a UTF-8 aware library of functions mirroring PHP’s own string functions. Does not require PHP mbstring extension though will use it, if found, for a (small) performance gain.
http://sourceforge.net/projects/phputf8