The other night, Channel 4 has broadcast this programme. That's some sort of spin-off from the trial we're working on at UCL (Valerie Curran is the principal investigator $-$ the whole group is really good and all nice people to work with!). The idea of the TV programme was to have a bunch of celebrities to try different forms of cannabis, to explore the hypothesis that it is the actual composition of cannabis that can make it harmful.
The point is that skunk is the younger and stronger version, which contains higher proportions of the "bad component" (THC), while hash is mainly made by a milder component (CBD), which seems to have far lower damaging effects $-$ in fact it can prove beneficial in some cases. A live blog detailing the programme is here.
I've mentioned this already (here, for example) and it's interesting from the stats point of view as we're implementing an adaptive design to this trial. We're collecting information on a set of volunteers and we'll continuously monitor the results, updating the uncertainty on whether several doses of the compound we're testing (based on CBD) is the most effective and can then proceed to a head-to-head trial phase against placebo.