Orkut is trying to catch up with Elgg - it looks mighty familiar! Elgg has been doing exactly this for several years.
We are creating a toolset that will go much further than this in enabling us to project personas. All Orkut (and Elgg) are doing here is filtering content based on access rights, which is a good start in recognizing the importance of the different facades we portray to others in real life, but not going anywhere like far enough. Our new tools will allow you to customise the look and feel as well - in effect, allowing us to have a different home page for every grouping of people we care about. It's still in development but, if they pass the tests and trials, the tools will be coming to Athabasca Landing before very long.