update changelog release date and bump version for 2.1 release (#3958)

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index d029ce6..49acbc6 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -4,10 +4,8 @@
 
 .. _v2-1:
 
-2.1 - `master`_
-~~~~~~~~~~~~~~~~~
-
-.. note:: This version is not yet released and is under active development.
+2.1 - 2017-10-11
+~~~~~~~~~~~~~~~~
 
 * **FINAL DEPRECATION** Python 2.6 support is deprecated, and will be removed
   in the next release of ``cryptography``.
diff --git a/src/cryptography/__about__.py b/src/cryptography/__about__.py
index e99a87d..3775996 100644
--- a/src/cryptography/__about__.py
+++ b/src/cryptography/__about__.py
@@ -14,7 +14,7 @@
                " and primitives to Python developers.")
 __uri__ = "https://github.com/pyca/cryptography"
 
-__version__ = "2.1.dev1"
+__version__ = "2.1"
 
 __author__ = "The cryptography developers"
 __email__ = "cryptography-dev@python.org"
diff --git a/vectors/cryptography_vectors/__about__.py b/vectors/cryptography_vectors/__about__.py
index 951ef35..d1a0145 100644
--- a/vectors/cryptography_vectors/__about__.py
+++ b/vectors/cryptography_vectors/__about__.py
@@ -14,7 +14,7 @@
 
 __uri__ = "https://github.com/pyca/cryptography"
 
-__version__ = "2.1.dev1"
+__version__ = "2.1"
 
 __author__ = "The cryptography developers"
 __email__ = "cryptography-dev@python.org"