Bostrom is working on a paper showing how existential risk prevention can be seen as the most important task for humanity (PDF and HTML).

From the last section ("Outlook"):

We have seen that reducing existential risk emerges as a dominant priority in many aggregative consequentialist moral theories (and as a very important concern in many other moral theories). The concept of existential risk can thus help the morally or altruistically motivated to identify actions that have the highest expected value. In particular, given certain assumptions, the problem of making the right decision simplifies to that of following the maxipok principle.