I've seen a couple of recent articles talking about how Facebook has turned on it's platform developers with it's most recent announcements. Fortune magazine has an article today entitled Fear Among Facebook Developers which states

Zuckerberg wouldn’t deny it. On stage at the Web 2.0 conference in October in San Francisco, he acknowledged that his company reserves the right to build anything it wants and compete with any of its independent developers, but that the company intends to do this fairly. “We need to make sure we have the flexibility to do what we need as the platform grows—to be flexible enough able to add in the next big component [like the News Feed],” he said.

Yesterday Erick Schonfeld wrote an article on TechCrunch entitled iLike vs. Facebook: The Battle For The Music Artist that contains the following excerpt

Instead, Facebook is treating music artists just like any other brands, which can also set up their own Facebook pages, collect fans, and market to them directly. Yet, when it comes to music artists, one of Facebook’s most popular application developers, iLike, is doing the exact same thing.
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So if you are a music artist, you now have to make a decision: Do you go with the iLike page as your main Facebook page (and take advantage of the nearly 10 million members who use the iLike app), or do you go with your own advertiser page on Facebook? Case in point: the new Facebook page for 50 Cent (shown left) had only three fans when it first went up just after midnight, compared to 1.2 million fans on his iLike page on Facebook.

This is a tale as old as the hills. Software platforms evolve and often this means incorporating features that were once considered as "features to be provided by others" as core parts of the platform. There are thousands of examples of application developers adding value to a platform that eventually became features of the platform due to popular demand. Whether it is adding a TCP/IP stack to the operating system, tabbed browsing to a Web browser or adding persistent searches to a Web mail application, it's all the same story. It is hard to argue that it isn't better for users such functionality to be a native part of the platform or underlying application, however it often leaves the platform developers in a lurch.

If the application developer cannot find a new way to add value to the platform then their usefulness to users comes to an end. This doesn't make it a slam dunk that once the platform vendor sees the value added by an application on it's platform, that things will eventually go sour for the application. There are many examples of vendors trying to compete with an application on their platform only to concede defeat and then try to acquire the company; PhotoBucket's acquisition by MySpace and Oracle's attempt to acquire BEA are two recent examples. [Editors note - I suspect that iLike vs. Facebook will end up going the same route as well]. In other cases, entry into the application space by the platform vendor helps to validate the market and draws more visibility to it from users.  

At the end of the day, articles like the ones I've mentioned above serve to prove that Facebook has actually built a viable and successful platform given that it is following the patterns of other successful platforms from the past several decades of the software industry.