This includes Facebook, Twitter, Picasa, Yelp! as well as other mundane sorts of sources like calendars, databases, CRM systems and so forth...
So what there is to watch for next is how well systems offer to fit together. This is why I think it's silly to engage in silly conversations like "Which is better, Facebook or Twitter?" The answer to that question is simply, "Yes!" I use them both together. And each one is better than the other.
Today I was impressed with how well Yelp! integrates with Twitter. For people who are yelp-ers, it's very convenient for their latest review to be pressed forth into Twitter-space without an additional effort. But what impressed me is the care with which Yelp! integrated the systems.
They use Twitter OAuth to create the linkage between their systems. It means that your credentials to log in at Twitter are passed safely between Yelp! and Twitter. They asked me kindly if I wantd to allow the connect, and then they finished the process by letting me know precisely how to turn it off if I changed my mind.
They also assured me that my reviews would only be announced on Twitter after I'd authorized it. Every possible measure was taken to engage me and invite my permission. This is how it's supposed to be done!
Now I haven't made a careful analysis of the security measurs in effect at Yelp! I'm merely speculating about OAuth on the basis of other things I saw. I didn't confirm that myself.
Yet I am impressed enough with the polish applied to the process of connecting the systems that I'm certain every care was taken with my credentials.
Good job Yelp!