Probably the feature most requested for MWN has been for some way to collect several documents together into a project. With document groups, that request has been fulfilled.
If you look at the document list, you'll notice that for each document, the word count checkbox is gone. In its place is a round button, colored to represent which document group that document is a member of. Initially, all these buttons are black (that's the default value). To change a document's group, simply click on the button. This will bring up an overlay that will allow you to choose which group to assign the document to.
Documents in the same group stick together in the document list. Documents in the same group contribute their word count to the word count total for the group. Finally, document groups are sorted in the order that they are shown in the overlay.
When designing this feature, I tried to strike a balance between functionality and ease of use. I think that I've achieved that goal, but I'd like to hear what you think of the document groups feature.
iPhone users - fear not! I have submitted an update to the MWN iPhone app and it is currently pending approval. I'm hoping that the update will appear in the app store within the next two weeks.
If anyone runs into problems or has any questions, feel free to drop me an email at email@example.com.