We are happy to announce that the Google Contacts Data API now
supports OAuth. This is our first step towards OAuth enabling all
Google Data APIs. Please note that this is an alpha release and we may
make changes to the protocol before the official release.  I will be
at the OAuth hackathon tomorrow to get feedback and help consumers
integrate.

Here are the three end points used in OAuth to get a token:
https://www.google.com/accounts/OAuthGetRequestToken?scope=http://www...
https://www.google.com/accounts/OAuthAuthorizeToken
https://www.google.com/accounts/OAuthGetAccessToken

To register for a consumer key / upload your RSA public key:
https://www.google.com/accounts/ManageDomains
(see http://code.google.com/apis/accounts/docs/RegistrationForWebAppsAuto....
for help on registering your domain)

Caveats:
- We currently only support RSA-SHA1 mode.
- The consumer key is the domain hostname you registered.  Currently
there are no consumer_secrets.
- The scope parameter specifies the URL identifying the service to be
accessed. See http://code.google.com/apis/contacts/developers_guide_protocol.html
for details about the Google Contacts Data API.

You can download a sample client at http://weitu.googlepages.com/GoogleDataOAuthSample.jar.
Alternatively, Andy Smith (termie) has written a php test server
(http://term.ie/oauth/example/client.php?sig_method=RSA-SHA1) that
provides an easy way to test getting OAuth tokens with RSA.  It uses
the example key pair on the OAuth wiki (http://wiki.oauth.net/
TestCases).  We have set up a test consumer with
consumer_key=weitu.googlepages.com<http://weitu.googlepages.com> that uses the same RSA key pair for
you to test with.

Let me know if you run into any problems,

Wei