Google Wave may be on its way out, but a lot of the features that made Wave so great at collaborating already have or seem to be making their way into Google Docs. Case in point: Today, Google Docs incorporates live text highlighting to Docs.
...to really work well together, it helps to know what [your collaborator is]about to do. Today we've made it much easier to anticipate the changes other editors are about to make.
You can now see the text that other editors are highlighting as they select it. So if someone is about to delete something on your screen or drag text somewhere else, you'll see them highlight that text before anything changes.
Collaborative highlighting in documents [Official Google Docs Blog]