I believe that Mark mentioned (during his keynote speech) that over half of their user base is over 25 yrs old now. Facebook will probably be hot until somet

I believe that Mark mentioned (during his keynote speech) that over half of their user base is over 25 yrs old now. Facebook will probably be hot until something an order of magnitude better comes along, and even then many people will not want to switch (inertia). Add to this the open approach (API + site integration), and it isn't too far a stretch to see them becoming the standard social operating system.