Starting a new thread since this is 2012 news.
Many new features to come, but with the roll out into NFL 2012 today we have implemented full functionality of the co-owner option. Owners now have the option to appoint up to 4 co-owners to their team (so you can have 5 total owners per team if you wish). All you have to do is go to Team->Team Owner Options->Add Co-Owner and you're all set.
Source: Their Facebook page.
This means I'll be able to open a couple more slots next year as I'll just sign on as a back-seat owner in a league or two so I can still herd the cats without the stress of trying to actually manage five different fantasy teams every week.
Edit: This will also, by default, reduce the opportunities for promotion/relegation anomalies.