I believe documentation is currently being developed. But in the meantime, the best place to look for docs on swift's API is the developer docs for Rackspace's Cloud Files.

http://www.rackspacecloud.com/cloud_h...

Be sure to ignore the Rackspace-specific pieces like the CDN integration.

We're working on a docs.openstack.org site for the Bexar release which will contain a developer guide for OpenStack Object Storage that is very similar to the Cloud Files doc (that document is our starting point). I hope to have more specifics about authorization in the guide by February. Thanks for asking about the doc. :)