There seems to be a difference between php 5.1 and 5.2 in how wordwrap counts characters (all on Mac OSX 10.5.2):
/Applications/MAMP/bin/php5/bin/php --version
PHP 5.1.6 (cli) (built: Sep 8 2006 10:25:04)
/Applications/MAMP/bin/php5/bin/php -r 'echo wordwrap("In aller Freundschaft (50)_UT", 20) . "\n";'
In aller
Freundschaft
(50)_UT
php --version
PHP 5.2.5 (cli) (built: Feb 20 2008 12:30:47)
php -r 'echo wordwrap("In aller Freundschaft (50)_UT", 20) . "\n";'
In aller
Freundschaft (50)_UT