Note on: "Inevitability of Plate Tectonics on Super-Earths" by Valencia,   O Connell and Sasselov, arXiv preprint 0710.0699
  Valencia et al. recently claimed that the mass of a Super-Earth (SE) is a sole factor in determining whether a SE is tectonically active or not. However, mass resolving astrometry is unable to discern between a SE and its moons if any. The fact that no exomoons have been discovered yet is rather a matter of instrumentation imperfection at the present, not of physical absence of exomoons. This, with recently discovered relationships between geometric and physical properties in astronomical bodies (Transiting planets; the Earth) makes it impossible to know yet if the Wageners (here constraining) supposition on somehow-tidally caused tectonics holds universally or not also. 
Mensur Omerbashich