Surface tension is sort of like the level of gravity an object has towards itself to keep itself together, such as when water beads on a waxed car or a drop of dew. Different materials have different levels of surface tension, with Jelly being much higher than Water... Theoreticly it should then be possible to create liquid like materials that can hold their shape (although shape would be limited to organic curves or bubbles) like jello can, and can also be passed through like water.
The trick is that the jell like material, in order to be useful needs to have a strong enough level of surface tension to keep air or water in/out and still be able to allow other things such as people, to pass through it.
In its more simple form this type of technology makes a very useful airlock, in that the subject simply needes to pass through the jell barrier. The barrier keeps the air on one side and the water or vacuume on the other side seperate while the increased mass of the subject may simply walk through. Fast moving objects run the risk of rupturing the surface tension of this form of airlock.
For comparison, the standard airlock operates by the subject entering the airlock, sealing himslef off within it. Airlock machinery then cycle the atmosphere out to change it to resemble the area he is going into. This takes anywhere from several seconds to several hours depending on the atmospheres being changed. During the change the subject must rely entirely on its own self contained life support, which can be problimatic if there is an emergency. The Surface Tension based airlocks work instantaniously.
Note: If the life support being used by the subject is sub-standard, then the atmopheric pressure change experienced by passing through the Surface Tension based airlock can cause the subject to get the bends.
Materials useing strong levels of surface tension can also be used to create air bubbles around larger fortifications such as cities, or even stronger surface tension levels enable the materials to be construction materials in their own right. This enables the construction of underwater cities protected by surface tension supported domes, or even entire space ships or space stations.