  In contrary to customarily consideration of the Jahn-Teller theorem for
3d-ion compounds in the orbital space only we point out that it has to be
considered in the spin-orbital space. It is despite the weakness of the
intraatomic spin-orbit coupling. A direct motivation for this paper is an
erroneous claim of a recent Phys. Rev. Lett. 96 (2006) 027201 paper that the
high-spin t2g4eg2 state of the 3d6 configuration is not Jahn-Teller active.
