There are many benefits and some liabilities to Internet Communications in the classroom. By far, the benefits outway the liabilities.  I've addressed these issue separately below in three specific scenarios for using communications in the classroom
a) interactive videoconferencing (in any format, structured/unstructured, formal/informal, professional/amateur equipment)
b) internet telementoring (distance learning) 
c) telecollaborations between two groups of students

Benefits:
> Enables multi-curtural learning
> enables prejudice reduction,
> Provides potentially exotic experiences with places, with people (telementoring)
> appreciation of multiple perspectives.
> Potentially puts everyone on the planet in touch with everyone else on the plan
> Telecollaboration allows students in classrooms around the world to work on collaborative (and cooperative) projects without regard to physical location.  Naturally issues of time and language differences must be addressed. They are addressed in a separate paper I wrote on this subject.
> Choice of international collaborative projects for the two sets of students to work on is important
Frequent written exchanges between the students on both sides of the collaborative portal are essential.  Research shows that carefully planned Critical thinking exercises must be employed to fully benefit from cross cultural education. (ISTE's Journal of Research on Technology in Education (Vol 37, Number 1, Fall 2004) 
> distant learning
> real-time collaboration across schools, across continents (Classroom-to-classroom collaborative projects.)

Liabilities:
>  puts physical distance between teacher and learner or between two learners. This is not necessarily a bad thing, especially if the electronics facilitates collaborating that might not otherwise have occurred.
> Potential issue of in-class IM chat and email, etc. This can be easily controlled by such systems as NetOP (a review of the NetOP system) and other Class-pc management systems.  (As we have installed at CWP)
>Privacy, security issues are looming large in many schools  - New private networks, maintained by many states and restricted to academic use have been created.  Ultimately this becomes an issue for the local community to deal with.  One can easily become paranoid about the safety of one's children, but there are methods to protect our children's security while provide them valuable experiences on the internet.
> Also Internet2, (http://www.internet2.edu)  a new secured internet protocol, addresses many of today's internet security/privacy issues. Perhaps, LIU should become involved in actively participating in the formation of this new protocol standards that is meant specifically to meet the needs of universities, and K-12 schools.
> Inappropriate web site surfing
> violation of AUP
> personal (misuse)use of computer
> There are substantial differences in a) hardware b) application c) conclusions, between video conferencing in K-12 classroom vs telementoring between Irv and the Montana college classroom.
(See "Videoconferencing for K-12 Classrooms", Camille Cole, Kecia Ray, Jan Zanetis, ISTE publication: A Program Development Guide, Copyright 2004. Very Practical Book, from page 1.

Technical issues raised for video conferencing is whether identical CODEC's must be used on either side of the portal connection.  Must each side of the conference agree to common CODEC and /or use common O/S and/or O/S Version and/or O/S Version Build, etc.

Some of the comments below were written some weeks ago for the Forum Discussion on Communications aspects of the Internet. They are certainly relevant here.  The notes have been updated

As mentioned many times throughout various forum discussions, the communications aspects of the internet is one of its chief assets.  Many new hardware configurations are being created that allow sophisticated multi-party videoconferencing without too great a cost.  One such configuration is offered by Citrix, which allows the use of very inexpensive (and often old) pentium based computers to be used in an online internet eperience.  The Citrix system uses "thin clients" allowing all applications and application processing to reside on the main (Citrix) server and to use the "dumb-terminal" simply as an input/output device (i.e. keyboard/mouse and monitor).  My first reaction to this efficient use of thin client technology was skeptical since I imagined that the on-going support of these computers, especially those place in students' homes, would be a nightmare for tech-support personnel in the schools.  But after talking to various technology coordinators at various school districts that do indeed use a Citrix architecture, the problems are much more manageable than I imagined.  I would have expected that the use of older equipment, even refurbished, used as a dumb-terminal in a thin client environment would cause tech support staff to be busy supporting parents and children who are not familiar with computer basics.  But the experiences I have heard from my colleagues and fellow graduate students tell me otherwise. 

In my investigation of various interactive videoconferencing (IVC) packages, I found a few worth nothing The VSEE system  creates a video wall for a telementoring environment.  In this configuration the mentor sitting at his/her computer can watch a wall with each streaming video of all the participants.  The mentor can control "who has the floor."  It is a wonderful system - ironically invented by a graduate student named Milton Chen (no relation to the GLEF Milton Chen whom most of us know).