I am very strong believer in this type of project, have been doing it many years, as a former employee of one of the largest computer companies in the world I felt it was my responsibility to explain the benefits of this kind of thing to others and as a result won an award for work done towards the cause.
The project I contributed towards is World Community Grid. I am not trying to make people come across to this rather than supporting the causes of others who are also doing a fantastic job, I would simply like to show this information so that others can view the amazing work people are doing.
Supercomputers such as Roadrunner (IBM) , Blue Gene (IBM) and I believe K which is a japanese supercomputer are all used for this sort of thing. To give an idea of how powerful these supercomputers are the K computer can apparently do "8 quadrillion calculations per second", not bad, however this is really only the power of around 28,000 PS3, so imagine how much we can do as a community if every idle computer in the world was to contribute. We could potentially solve (or atleast attempt to) some of the planets greatest problems, like cancer, aids, starvation along with many other problems.
Anyway, thats all I really had to say, I just hope that with everyone putting a little effort in that we can potentially reach our goal of solving some of the world greatest problems within the next decade. Its certainly possible.