Community contributions and copyright assignment

When an organization wants community contributors to signed a copyright assignment, the question is not simply whether they are expected to do the right thing wrt the community. It is about what might happen to them in the future, in particular public companies are susceptible to corporate takeovers, and privately held companies may sell out to someone else.

Although both MySQL and VirtualBox were already selling code under closed-source licenses before acquisition, the rapid change in ownership to Sun, and then Oracle, nicely highlights how your work can end up in the hands of unexpected players whom you might well not have given copyright assignment to had they been the original owners. So pretty much the only people I'd be happy giving copyright assignment to would be independent, non-profit foundations which are safe from corporate takeovers.