Telepresence is an area of virtual reality technology that gives the user the impression, as realistically as possible, of being in another place, or perhaps interacting with a real object. Sight and hearing are reasonably straightforward to emulate, assuming enough computing power and sufficiently accurate visual and audio displays.
Even systems limited to vision and sound can have unexpected social consequences.
Full telepresence, however, will require senses other than sight and hearing. Tactile feedback (i.e., touch), is one of the first to be needed. The proprioceptive sense, on where the user is located in three-dimensional space whether simulated or remote, is another.
This is now being done in flight or surgery simulators for training. Telepresence is also done to allow a human to control a device that is smaller than the user could manipulate reliably with direct touch, as in robotic surgery, or at a distance -- telesurgery operations have been performed, over high-speed communications links, across the Atlantic.
Effective surgical systems, whether for training or actual operations, need the user to have tactile (i.e., touch) feedback, implemented with sensor-lined gloves or hand controls that "push back" depending on the resistance encountered by the remote sensor. Some surgical   and interventional radiology  devices are normally controlled by knobs or joysticks, into which it is relatively simple to put the resistance aspect of the tactile sense.
Sensations such as heat, moisture, and pressure on one's skin are much more complex. The current approach uses some type of glove line with sensors and actuators. Neurologic researchers are exploring safe ways to stimulate nerves to provide sensations of heat, the tickle reflex, or moisture.
The proprioceptive sense may not be a unique sense, but, subjectively, it involves sensing one's own body orientation.
Military and commercial airline flight simulators provide the sense not only with visual and auditory cues, but with cockpits, equipped with standard pilot seats, that can yaw, pitch and roll. Some simulators, indeed, have sufficient roll capability that the platform will rotate and the user will hang upside down, restrained only by a seat belt. 
Acceleration is much harder to simulate, although visual cues can suggest it. In increasingly realistic proprioceptive and tactile telepresence, safety begins to become a distinct concern. Hypothetically, assume a virtual reality training device for a martial art. How hard can the motors and actuators of the telepresence system press on the user? Are there situations in which only the danger of injury, even mild injury, is needed for full reality?
This is not a hypothetical question. Systems with visual cues alone, perhaps supplemented with touch-sensing gloves and a treadmill-like platform that senses walking, have caused intense vertigo in subjects. Sometimes, this is caused by unacceptable delay between human user and system response. In other cases, the human's action and the virtual environment response are in perfect synchronization -- but what if the user overbalances, such that he would naturally fall?
Exploring disorders of proprioception
Vertigo, brought on by cues or disease, is being evaluated with virtual reality. 
Teledildonics is a technical term in virtual reality, coined semi-humorously by Ted Nelson, the inventor of hypertext. To put Nelson and his credentials in context, Tim Berners-Lee created the Web by making hypertext work across networks with a standard URL scheme. Nelson proposed it as a thought experiment on what it would take to sense sex acts through telepresence virtual reality systems. 
Conceptually, some number of people wearing body stockings lined with pressure sensors could sense movement of a person next to them in the virtual environment, and, if tiny push-rods could be placed alongside to the sensors, the suit could give the basic tactile sensation of pushback that contacting another body next to yours. Clearly, the applications for such things go well beyond sexual experiences.
Just at this relatively primitive level, it was now a problem to decide the amount of computing power needed to sense and transmit this in real time, and then for a network to carry it. Of course, just pressure isn't enough.
- "See All Your Co-Workers' Flaws in HD With Telepresence", Wired, 11 June 2007
- European Institute of Telesurgery, Laparoscopic Training Centre (Strasbourg, France)
- Rassweiler, J & T. Frede (2002 Jul-Aug), "Robotics, telesurgery and telementoring--their position in modern urological laparoscopy.", Arch Esp Urol. 55 (6): 610-28
- Ma, X. et al. (2006), "A virtual reality simulator for remote interventional radiology : Concept and prototype design", IEEE transactions on biomedical engineering 53 (8)
- Chien Wei Chia, Low Cost Virtual Cockpits for Air Combat Experimentation
- Neurovestibular Adaptation Integrated Research Team, Team Goals
- Opendildonics.org Wiki