Does T* represent a Crossover or a Hidden Phase Transition?

Is there a single pseudogap scale or are there multiple scales?

What is the relation between the Pseudogap (above Tc) and the Superconducting Gap (below Tc)? Is the system above Tc a phase-disordered d-wave SC? Are there pseudogap effects below Tc, e.g. two distinct gaps below Tc?

Evidence for spin-charge separation in pseudogap region?

What happens to the pseudogap (as a function of doping) as one approaches the SC-insulator transition? Quantum critical effects in the pseudogap regime?

Effect of magnetic fields on the pseudogap phenomenon?

Materials issues: similarities and differences between pseudogap phenomenon in YBCO, BISCO and LSCO.