Lauren Formalarie at SayItSocial.com has two great posts (here and here) regarding cross-cultural corporate social networking. Given the multinational reach of many organizations, any external or internal corporate social networking strategy needs to address differences in culture.
Depending on the level of diversity a company is trying to reach, cross-cultural research could be a massive assignment. Also, testing the theories using small test groups throughout the research process can be a lot more beneficial than creating errors publicly.
Organizations attempting to use social media platforms to support human capital initiatives (e.g. recruitment, retainment, inclusion, affinity groups, etc.), should take the same advice. Even organizations with domestic operations will likely have various cultures represented in their workplaces.
Bottom line: do your research!