The company that can best walk this tightrope will win.
Some of the areas we'll see this in are:
- social search
- location-based services
- personalized recommendations
- purchasing history (think Blippy + Amazon)
- social network ranking and filtering (along the lines of what Buzz was doing)
The big question for me is, will users be willing to give one big player all their data? Or will we have a system, much like in personal financing, in which many individuals "invest" their data with several companies and use "brokers" to manage it. I want to favor the latter paradigm because this way, you don't have one big player locking it down at users' expense.
Google and Facebook playing keep-away with each other opens up a big opportunity for the small guys to come in and be that one broker who will help users manage their location-based data, their status updates, etc and offer them great services. Greplin is one such player and I'm sure there will be others.