I was introduced to GoogleDocs about a year ago. Zoho looks a little more user friendly from what I can tell as well as more aesthetically pleasing. In general, collaborative writing tools are a great idea for groups that frequently work together. They require less work than the Track Changes feature in Microsoft Word to view and adopt changes to the original document. There is only one version of the document floating around at any one time and changes are made real-time.
Though the advantages are obvious for groups that are geographically dispersed, it is also beneficial to those working within the same building. Time in meetings usually spent hashing out the wording in a new policy or report could be minimized through collaborative writing tools. The group working on the project could be given a time frame in which to submit changes and suggestions to the document and then all the suggestions could be reviewed at a final meeting.
The use of GoogleDocs and Zoho could definitely promote free speech in the office place offering everyone an equal chance to have their say without having to stand in the spotlight. However, users will need to remember common courtesy to keep from flaming a coworker for a suggestion. Users need to use the same courtesy online as they would in person.