diff --git a/oauth2/__init__.py b/oauth2/__init__.py
index b0f61fa5..a965fc71 100644
--- a/oauth2/__init__.py
+++ b/oauth2/__init__.py
@@ -309,8 +309,14 @@ def to_header(self, realm=''):
  
     def to_postdata(self):
         """Serialize as post data for a POST request."""
-        return urllib.urlencode(self)
- 
+        return self.encode_postdata(self)
+
+    def encode_postdata(self, data):
+        # tell urlencode to deal with sequence values and map them correctly
+        # to resulting querystring. for example self["k"] = ["v1", "v2"] will
+        # result in 'k=v1&k=v2' and not k=%5B%27v1%27%2C+%27v2%27%5D
+        return urllib.urlencode(data, True)
+
     def to_url(self):
         """Serialize as a URL for a GET request."""
         return '%s?%s' % (self.url, self.to_postdata())
@@ -325,7 +331,7 @@ def get_parameter(self, parameter):
     def get_normalized_parameters(self):
         """Return a string that contains the parameters that must be signed."""
         items = [(k, v) for k, v in self.items() if k != 'oauth_signature']
-        encoded_str = urllib.urlencode(sorted(items))
+        encoded_str = urllib.urlencode(sorted(items), True)
         # Encode signature parameters per Oauth Core 1.0 protocol
         # spec draft 7, section 3.6
         # (http://tools.ietf.org/html/draft-hammer-oauth-07#section-3.6)
@@ -571,7 +577,8 @@ def set_signature_method(self, method):
         self.method = method
 
     def request(self, uri, method="GET", body=None, headers=None, 
-        redirections=httplib2.DEFAULT_MAX_REDIRECTS, connection_type=None):
+        redirections=httplib2.DEFAULT_MAX_REDIRECTS, connection_type=None,
+        force_auth_header=False):
         
         if not isinstance(headers, dict):
             headers = {}
@@ -589,13 +596,23 @@ def request(self, uri, method="GET", body=None, headers=None,
 
         req.sign_request(self.method, self.consumer, self.token)
 
+        if force_auth_header:
+            # ensure we always send Authorization
+            headers.update(req.to_header())
+
         if method == "POST":
-            body = req.to_postdata() 
+            if not force_auth_header:
+                body = req.to_postdata()
+            else:
+                body = req.encode_postdata(req.get_nonoauth_parameters())
             headers['Content-Type'] = 'application/x-www-form-urlencoded'
         elif method == "GET":
-            uri = req.to_url()
+            if not force_auth_header:
+                uri = req.to_url()
         else:
-            headers.update(req.to_header())
+            if not force_auth_header:
+                # don't call update twice.
+                headers.update(req.to_header())
 
         return httplib2.Http.request(self, uri, method=method, body=body, 
             headers=headers, redirections=redirections,