According to this post in Allfacebook blog (and as is well known), at the same time as Facebook is encouraging outside developers to develope applications using the Facebook platform, it is also developing new features and applications itself – these being possibly the same as what the outside developers have been working on. This happened to developers of Friendmates application when Facebook launched similar feature of its own – making Friendmates practically useless.
This kind of strategy may not be the wisest one for Facebook, as while trying to establish its position as the social network of the Internet, Facebook is dependend on co-operation of thousands of outside developers. If it keeps on stepping on application developers’ toes, they most certainly will feel disencouraged to dedicate their time and money on something their partner may at any time make worthless.
If Facebook wishes to become truly an infrastuctural web service, they should dedicate themselves on developing their platform and creating such services that will enable the application developers to develope, market and monetize their services more easily. They could look for an example at Google, which has helped the monetization of online services hugely with their AdSense/AdWords-product.
It is enough for Facebook to have the basic working social infrastructure (however, finding friends easily may well be essential part of the infrastucture). The rest can be developed by outside developers – thus benefiting both the network and the developer.