On PHPBuilder.com today there's a new tutorial about updating your application's Twitter authentication from the basic method to OAuth (which will become the new standard).

Twitter provides an API for developers to build applications on top of it. The API has supported basic authentication over HTTP, but beginning in June 2010 Twitter is discontinuing basic authentication and migrating all Web and desktop applications to OAuth (Open Authorization). Although simpler to implement, basic authentication had its drawbacks. [...] OAuth on the other hand provides a more secure way to authenticate users and allows a persistent access token, which application developers can then consume.

They explain a bit about how OAuth works as compared to the basic authentication method (complete with a graph) and how to use the OAuth Twitter library to make the connection between your application and the Twitter servers.