Current Mueller polarimeters, with either spectral or angular resolution, feature high enough precision and speed to be suitable for many demanding applications, with specific advantages over conventional spectroscopic ellipsometry (SE). Due to the simultaneous determination of depolarization, birefringence and diattenuation Mueller polarimetry (MP) can open new fields in surface and thin film characterization techniques with new and very powerful intrinsic analyses of roughness and/or anisotropy. For more conventional applications, such as scatterometry (i.e. the determination of the shape of periodic structures from optical measurements, mostly used in microelectronics), MP may overpass SE in terms of systematic errors and/or measurement spot size, as discussed from two examples. However, numerical simulations remain a key point to take full advantage of MP capabilities for the new challenges emerging in nanometrology. (C) 2010 Published by Elsevier B.V.