Perl's implementation of unicode changed quite a lot between 5.6.x and 5.8.x. It is, so I read, very much improved in 5.8.x but with that improvement came the need for a few non-backwards compatible changes and some extra warnings it seems. I've yet done precious little with it.
Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail
"Memory, processor, disk in that order on the hardware side. Algorithm, algoritm, algorithm on the code side." - tachyon