Perl.com: What’s New in Perl 5.6.0?

“The largest change in Perl 5.6 has to be the introduction
of UTF-8 Unicode support. By default, Perl now thinks in terms of
Unicode characters instead of simple bytes; a character can, as the
CJK people already know extremely well, span several bytes.

All the relevant built-in functions (length, reverse, and so on)
now work on a character-by-character basis instead of byte-by-byte,
and strings are represented internally in Unicode.”

“As usual, Perl now supports more computers than ever before,
with the addition of six new supported platforms; notably, the
GNU/Hurd is now supported, as is the Psion 5.”

“Perl’s threading has been drastically reworked. It’s still
experimental, and there’s still every expectation that the current
implementation may be thrown out and started again, but Perl now
supports two different types of threads. …we’ve got the threads
that existed in Perl 5.005 – your program can thread, and each
thread can have its own variables and stashes, controlled with the
Thread module as before, and these threads have become slightly
more stable – but we also now have interpreter-based threads.”