Rather than trust busting, why not start with relaxing the federal laws which forbid the development of third-party applications? The limits on third-party apps are legal, not technical. It is not technically challenging to build an application that collects Facebook credentials and then presents alternative views and features. It could, for example, finally be possible to see a time-ordered view of your friends' pos…
Suppose the CFAA wasn't applied so indiscriminately, but Facebook still didn't want third-party clients to access their data and there was no requirement for them to do so. So they make sure there's no publicly-available API, at least with any terms of service that let you build a true third-party client. Assuming there is still some legal mechanism to make unauthorized access to computer resources illegal, then tapping into Facebook's private APIs counts. Doing what 3Taps and PadMapper did -- just scraping data -- can be a Terms of Service violation (as can the private API access, presumably) and could conceivably even be charged as a copyright violation. It's asking for trouble. It's also potentially a constant cat-and-mouse game. And, last but not least, there's no guarantee that data scraping will actually get you the data that you need to do a good job of building a new business on top of Facebook's social graph.
What would be better, if you accept the original premise, is not new regulation, per se, but antitrust action specific to these companies forcing them to build open APIs. Simply saying "hey, Facebook can't sue you for data scraping anymore" just won't cut it.