You're right about the barriers to entry part. But barriers to entry are low enough for relative first movers like Facebook/Ning. When the market matures and there are several clones of these services, Facebook/Ning will have to rely on the lock-in to stay ahead of the competition.
There is a general trend in users' demanding openness in data, and maybe this will have to be a core feature of any new web-service/desktop-app to succeed in the future. But the general rule is that a business won't open the data if it doesn't have to.
There is a general trend in users' demanding openness in data, and maybe this will have to be a core feature of any new web-service/desktop-app to succeed in the future. But the general rule is that a business won't open the data if it doesn't have to.