work can be done by magnetic forces?Or can it not?

Well, can magnetic forces do work or not?The discussions on this topic seem to go on ad nauseum, but one thing that a majority seem to agree upon is that the magnetic (Bqv) part of the Lorentz force cannot do work on an unconstrained(or even constrained,depending on your point of view) moving charged particle.To be more precise there is no movement of the charged particle in the direction of the force.Looking at it another way ,the application of the magnetic force alone does not result in any energy changes.

Assuming that the magnetic field (Bqv) cannot do work on the particle does it mean that it cannot do work on anything?There seem to be many people who answer this question in the affirmative.Despite this it is easy to imagine events where work is done.Consider the following:

An observer is in a frame of reference such that there is a system setting up a B field which is observed to be stationary.A particle of charge q and velocity v then enters the field such that  it experiences the Bqv force. As a result the particle moves in its curved path.
All the time there is the force on the particle there is an equal and opposite force on that part of the system that sets up the B field (Newton's third law).The result is that this system moves from its initially observed state of rest.Due to momentum considerations this movement may be considered to be negligible but nevertheless there is movement and a transfer of energy.
If you are one of those who believe that the magnetic can not do work then here is just one of the questions that arises.What is the force/mechanism that is instrumental in the magnetic system picking up kinetic energy?

(Of course the whole event is much more involved than merely that which has been described above but I couldn't be bothered to write any more about it at the moment)