Most Google services have an API described by the Google Discovery Service. This includes both Apps APIs (such as Gmail and Drive) and Cloud APIs (such as Cloud Datastore and Cloud Storage).
Based on previous work by GDEs Adam Singer and Gerwin Sturm, the Dart Team has built an API generator to create Dart client libraries enabling access to Google services. We recently published the following two packages on pub.dartlang.org:
The googleapis package contains all the APIs that are available in a stable version. The googleapis_beta package contains the APIs that are currently in beta and possible only available through a Limited Preview program. We will be updating these packages on a monthly basis to ensure that they provide access to new services as they become available.
Along with the generated APIs, we have published a googleapis_auth package that handles all the different authorization models supported to access the APIs from different environments. Using googleapis_auth makes it easy to use the client libraries in a standalone application, on a Google Compute Engine instance, or in the browser.
To get started using the libraries, take a look at the GitHub repository googleapis_examples. The examples cover both Dart code that runs in the browser and Dart code that runs as a standalone program, demonstrating how to access Google Drive and Google Cloud Storage.
Please post on our discussion group if you have questions or comments on the client libraries. You can also file bugs on GitHub projects for the generator and the googleapis_auth package.
By Søren Gjesse, Software Engineer on Dart
Update (Sep 23, 2014): An article on using Google APIs Client Libraries with Dart has been added.