The good news:
"OAuth is the de facto standard for authorization today and is used by most modern APIs. Apps Script handles the OAuth flow automatically for dozens of built-in and advanced services, but until recentlyonly had limited support for connecting to other OAuth-protected APIs such as Twitter, etc. The URL Fetch service’s OAuthConfig class only works with the older OAuth 1.0 standard and only allows the developer of the script (not its users) to grant access to their data. To address this, we’ve create two new open source libraries"
The bad news:
"We believe that these open libraries are a better alternative to our previous solution, and therefore we are deprecating the OAuthConfig class. The class will continue to function until June 26, 2015, after which it will be removed completely and any scripts that use it will stop working We’ve prepared a migration guide that walks you through the process of upgrading your existing scripts to use these new libraries."