At frequencies where the skin effect dominates the conductor resistance of solid copper, it will definitely work - the inner part of a copper conductor is just dead weight when 90% or more of the current are carried in a layer a few µm below the surface. Since Integral produces antennas for up to 2.4GHz, I assume that they plan to use the metallized plastic in coax conductors.
Intresting... I assume you would need a larger diameter (cross-section) for the same current capacity. Still, this could be especially valuable in automobiles, the wiring harness weight is ~50 lbs, cutting that by 80% would help fuel economy. But I'm puzzled - if the current is carried by metal fibers (and not by the plastic itself), it seems like you'd need the same amount of metal. Also this seems like a great material for enclosures for laptops/cellphones/etc., as it is moldable but provides EMI/ESD/RFI protection.
Fascinating, but seemingly very backwards when environmental performance characteristics are considered. First, this is based on a polymer, presumably from a non-renewable resource. Second, it's not clear that it's easily recyclable - how are the metals and the polymers separated? Third, it probably requires the use of phthalates and possibly flame retardants, chemical substance classes that are coming in to scrutiny in Europe and elsewhere. On the positive side since the weight is lower it might cost less (and use less energy) to transport.