The next version of PHP, which saw its first release candidate today, has some really awesome new features. You can see a complete list of changes in the README, but here are the ones that caught my eye.

Classes

• Support for Traits (i.e., mix-ins; addresses the multiple-inheritance problem).
• Support for chaining from the constructor: (new Class)->method()
• Support for Class::{expr}() syntax.
• Closures inherit $this from the outer scope.
• Added ReflectionClass::newInstanceWithoutConstructor() to create a new instance of a class without invoking its constructor.
• Added a new typehint: callable

Improvements

• Array dereferencing and short array syntax: echo [1, 2, 3][0]
• json_encode() now supports these additional flags: JSON_UNESCAPED_UNICODE, JSON_BIGINT_AS_STRING, JSON_NUMERIC_CHECK, JSON_PRETTY_PRINT and JSON_UNESCAPED_SLASHES.
• Multibyte support is enabled by default.
• Faster unserialize() and ternary operator performance.
• IPv6 support.

Fixing the cruft

• ext/mysql, mysqli and pdo_mysql now use mysqlnd by default.
• Removed magic quotes, safe mode, register globals, allow call-time pass-by-reference, and more!
• Default character set is now UTF-8 instead of ISO-8859-1.