Clarify the versions and implementations of python supported.

README.rst

@@ -20,7 +20,7 @@ gevent_ is written and maintained by `Denis Bilenko`_ and is licensed under MIT
 get gevent
 ----------
 
-Install Python 2.5 or newer and greenlet_ extension.
+Install Python 2.5, 2.6 or 2.7, and greenlet_ extension.
 
 Download the latest release from `Python Package Index`_ or clone `the repository`_.
 
@@ -61,4 +61,3 @@ running tests
 .. _mailing list: http://groups.google.com/group/gevent
 .. _blog: http://blog.gevent.org
 .. _twitter (@gevent): http://twitter.com/gevent
-

setup.py

@@ -302,6 +302,7 @@ def run_setup(ext_modules):
             "Programming Language :: Python :: 2.5",
             "Programming Language :: Python :: 2.6",
             "Programming Language :: Python :: 2.7",
+            "Programming Language :: Python :: Implementation :: CPython",
             "Operating System :: MacOS :: MacOS X",
             "Operating System :: POSIX",
             "Operating System :: Microsoft :: Windows",