Significant changes to the Perl language in various versions:

(note: major new features are only added in major-version releases (eg. 5.10, 5.12, ...))

Perl v5.14

• when can be used as a statement modifier
• complete list

Perl v5.12

• ... operator added
• use 5.12.0 adds a number of different things at once
• each(), values() and keys() work on arrays
• complete list (errata)

Perl v5.10

• given and when keywords added, as a way to implement switch statements
• say keyword added
• state keyword added
  • backwards compatibility: Var::State
• // operator added
• more
• complete list (errata)

Perl v5.8

• complete list

Backwards-compatibility

• there are a LOT of these modules for Perl6 features... there are at least some for Perl5.x features.
• any::feature is an attempt at making these back-compat modules easier to use