Chat - Is this a real online tool or what?

The online teaching tool that sort of intrigued me is chat. My view of chat prior to reading of its use in online education was of a pretty lightweight, informal means of communication that didn't have a lot of substance. Good for saying, "How ya doin'?" or "Meet me at the SUB", but not much else. As it turns out, I was partially right (or mostly wrong!). I researched several journal articles through the Albertson's Library at Boise State University, using the search terms "synchronous communication". I selected two references to discuss.

One reference, "A Field Study of Use of Synchronous Chat in Online Courses (Spencer and Hiltz, 2002)", provided results as follows (paraphrased):
1) Chat was hard to schedule due to conflicting schedules of students and instructor. Works better if fewer students are online at one time.
2) Instructors complained that even when students agreed to a specific time, most did not participate
3) If students had no previous experience with chat, they tended to have a negative view of using it at all
4) Students who were required to use chat 2 or more times in class tended to rate it more "rewarding" than those who only used it once.
5) Chat sessions as virtual "office hours" seemed to be a good use of chat from both the student and instructor's perspectives.

In "Evaluating the use of synchronous communication in two blended courses" (Cox, Carr and Hall, 2004), their study compared the use of chat in two different courses, which highlighted the fact that chat is not universally suitable or applicable in the same ways. In one course, the students were asked to participate in discussions of only the topic at hand; in the other course, students were asked to engage in a highly competitive and interactive activity. In the first course the primary conclusion was that chat at most lent itself to development of more social cohesiveness in the class. In the second course, it was found that chat was quite useful for both mobilising group production as well as providing a self-documenting record of collaboration that occurred.

Learning Objective Definition: What learners should be able to achieve by the end of a learning experience.
Given the above definition, what can we say about the learning objectives applicable to chat as an online tool? Perhaps the primary one is: The student will be able to apply chat as an online tool as a means of synchronous communication in a variety of circumstances. I would like to hear from anyone who has applied chat effectively in whatever environment in which they operate!! Give me some feedback...