Twitter is beginning the long process of changing their API root URLs from
api.twitter.com/1/. This isn’t of much interest to ordinary Twitter users, but developers will need to update their applications sometime in the coming months.
The old URLs will continue to function for the foreseeable future, but Twitter wants to get developers using their new versioned URLs, to prevent potential foul-ups in the future, should they change something in a way that is less than backwards-compatible.
We haven’t yet determined how many versions will be supported at once or how long a version will continue to be supported once it’s deprecated. We’ll be figuring out answers to these questions once we spend some time supporting multiple versions and seeing how new APIs emerge and iterate. We suspect though that we’ll support deprecated versions for at least 6 months.
This is all part of their API version 2.0 roadmap.