Most of the wide-spread languages support Unicode and/or UTF-8 at least in some form; post-2K languages support Unicode quite commonly, but there are always few things to look after.
The magic quotes, and the safe mode… ‘nough said.
Fortunately, both of these are deprecated in new versions of PHP.
Unfortunately, most hostings are not that keen on updating PHP to the newest version (mainly they’re still stuck at the likes of version 5.1.x).
What to do?