it is drm - just a global rather than local one .i really hope those are just fantasies. i just wanted to show that it is not impossible. not that it will inevitably happen.
k. back on topic.
the main problem here is proof of work.
to make it work the scientific problem needs to be verifiable in a polynomial time while not being solvable in polynomial time (the P!=NP theory)
so a client can work for a certain time on the solution. and once found can be verified quickly.
another thing is that it has to be predictable so you can clearly define a unit of work
for example looking for extremely large prime numbers can be useful - and shouldnt be to hard to verify
http://w2.eff.org/awards/20000406_coopaward_pr.html https://www.eff.org/awards/coopyou can require that the first half of the number is identical to the last half of the previous one
and the difficulty can be adjusted by setting a lower limit on the second half of the number