Had the same problems with my own forum and unicode lately, but thankfully I found this in the PHP online manual:
“If you experience weird problems, like some UTF-8 characters (the Unicode character č and a few others in my case) seemingly being changed to garbage by mysql_query, you may need to do something like this before your actual query:
<?php
mysql_query(“SET NAMES ‘utf8′”, $conn);
?>”
So is this being done by WordPress? I think not because there are plenty of posts about the same issue. Any developer comments..?