Claire Cramer just spoke about their experiments in the Eot Wash group in Seattle. (The U.S. English name "Eot Wash" is a deliberately misspelled version of the name of the guy who did the first tests of the equivalence principle.) Everyone seems to admire the group at the University of Washington as the clear leaders in the field of all similar experiments such as the torsion balance tests of sub-millimeter gravitational forces and the Lorentz and CPT violation.
I am probably far too conservative for the physical idea that the Lorentz symmetry or the CPT symmetry are violated in a new, yet unknown way; for me, these questions were settled 100 years ago. Of course, this does not quite include the fifth force etc. - very large extra dimensions, new light scalar fields and so on - although I still believe that the probability that gravity gets modified at the multi-micron scale is vastly smaller than 50 percent.
Nevertheless, their technology involving all the subtle pendula and other things is a truly ingenious piece of experimental physics. Unfortunately I have not seen the full talk and cannot reproduce it here.