This article (a PDF file) discusses some possibilities (but it's from the NY Times, so take it for what it's worth): Physicists Finally Find a Way to Test Superstring Theory. Excerpt:
Unlike many of physics' far-out theories, the idea of a large extra dimension may be possible to test indirectly. Since gravitons are not so tightly confined as the other particles, sometimes they will stray into the surrounding hyperspace, becoming heavier than the ordinary variety. According to the theorists' calculations, it just may be possible to create momentarily these denizens of the fourth dimension using the Tevatron accelerator at Fermilab, where protons are slammed into antiprotons to produce energies measured in trillions of electron-volts.Physicists would not be able to detect heavy gravitons directly -- they would immediately fly off into the higher dimension -- but their existence might be inferred. Energy going into a particle collision must equal the energy coming out. If some is missing and all other possibilities are accounted for, physicists could surmise that the energy was spirited away by the heavy gravitons, carried off into hyperspace.
Something about the wording of that makes me imagine the Luddites cackling.