This is a good thing in itself, but it does raise the question of when a platform changes from being just 'open' to being so wide spread that it is considered as a public API. I'm not in a position to comment on why Peep wasn't updated to work with OAuth before it was released, but it does make you question who is responsible for maintaining the service levels of public API's.

If Twitter have published and promoted their API, surely it is their best interests to maintain its functionality, and ensure some level of backwards compatibility? This is a tricky point to argue, as on one hand it is very good that they are maturing their platform with new features and security, but on the other hand they do risk alienating the community they rely on by introducing new features that require third party application changes. By this I mean changes that require an update, and are not backwards compatible, rather than just not updating and missing out on any new functionality.

This is especially prominent in this instance as it affects the Twitter Application that actually ships with HTC Android handsets, so it is guaranteed to be quite widespread.