Recently I tried to do a project with Unicode support in Perl. Short summary: Perl 5.8.x must have, it kinda works but many things don't play nicely with Unicode (mainly XS modules) so often you end up looking for workarounds. More about this in my journal
P.S. To those who commented that they never needed Unicode: you are just lucky to be English native speakers and you are just lucky to have customers of same origin who never need anything other ASCII or at maximum Latin1 in their apps. I guess most of you never realize how bad state of things and how many apps are broken when you do need something out of ASCII or Latin1 domain. World would be much better place if software developers were not Unicode ignorant.