Powerful New Commenting Features in Gdocs

Google has launched a set of powerful new commenting features in Google Docs. Now, you can group comments together, use @mentions to call out people for comments, respond to comments via email and have those appear seamlessly in the document, and resolve and collapse comments to remove them from the page (but still view them later). It's best explained by watching the short video below. The features are only available in newly created Google Documents.