Google, in what appears to be a new initiative to make their APIs more secure for end users and easier to for developers to work with, has begun rolling out OAuth 2.0 support for its APIs. This brings about two major changes in how apps integrate with Google APIs.
First, the APIs will become much easier to work with, as it "focuses on client developer simplicity," according to the OAuth 2.0 site. An application merely needs to hang on to and use an access token to make secure calls.
Second, for your users, they will have richer control over how much access your app has to their data. Google has announced a new consent page, which will explain just what your users are getting in to, more clearly.
For now, OAuth 2.0 seems to be in Google's "experimental" phase, only allowing devs to access account information. At least one Google property has shown its serious about it. YouTube encouraged developers to check it out on the video site's developer forum.