  The Global mm-VLBI Array is at present the most sensitive 3 mm-VLBI
interferometer and provides images of up to 40 micro-arcsecond resolution.
Using this array, we have monitored the rotation of the innermost jet in the
quasar NRAO 150, which shows an angular speed of ~ 7 deg./yr. Future 3 mm
arrays could include additional stations like ALMA, GBT, LMT, CARMA, SRT,
Yebes, Nobeyama and Noto, which would allow to push VLBI at this wavelength to
sensitivity and image quality levels comparable to those of present VLBI at
centimeter wavelengths. This would improve our knowledge of the accretion
systems and the magneto-hydrodynamics of the innermost jets in AGN and
microquasars.
