Python 发布了 3.3.0 首个 beta 版本，该版本包含了 3.x 系列的很多改进内容，主要包括：

* PEP 380, syntax for delegating to a subgenerator ("yield from")
* PEP 393, flexible string representation (doing away with the distinction between "wide" and "narrow" Unicode builds)
* A C implementation of the "decimal" module, with up to 80x speedup for decimal-heavy applications
* The import system (__import__) now based on importlib by default
* The new "lzma" module with LZMA/XZ support
* PEP 397, a Python launcher for Windows
* PEP 405, virtual environment support in core
* PEP 420, namespace package support
* PEP 3151, reworking the OS and IO exception hierarchy
* PEP 3155, qualified name for classes and functions
* PEP 409, suppressing exception context
* PEP 414, explicit Unicode literals to help with porting
* PEP 418, extended platform-independent clocks in the "time" module
* PEP 412, a new key-sharing dictionary implementation that
   significantly saves memory for object-oriented code
* PEP 362, the function-signature object
* The new "faulthandler" module that helps diagnosing crashes
* The new "unittest.mock" module
* The new "ipaddress" module
* The "sys.implementation" attribute
* A policy framework for the email package, with a provisional (see PEP 411) policy that adds much improved unicode support for email header parsing
* A "collections.ChainMap" class for linking mappings to a single unit
* Wrappers for many more POSIX functions in the "os" and "signal" modules, as well as other useful functions such as "sendfile()"
* Hash randomization, introduced in earlier bugfix releases, is now switched on by default

详细改进内容：
     http://docs.python.org/3.3/whatsnew/3.3.html

下载地址：
     http://www.python.org/download/releases/3.3.0/