As a solo developer working out of my bedroom I can't afford to be sued by a multi-million dollar corporation, so I've taken the site down before I have any customers to disappoint.
The code that Flamingo was designed to host and configure is available on Gitub, as it was from the beginning. I recommend you do not run it on a publicly accessible server unless you want a cease and desist email from Twitter Platform Operations.
I have been accused of “resyndicating content”. By my definition Flamingo was [going to be] a hosting service allowing you to configure your own back end services for running your own Ajax-powered Twitter apps. It was not an open proxy. It was simply running your app - as you - as securely as possible to provide your front end with only the content it needed, and under your complete control.
Accessing the Twitter API from your front end application via your back end application is not explicitly against Twitter's terms, although it is strongly discouraged. The advice is that Ajax calls should be securely made to your own back end. I quite agree with the last point, which is why Flamingo had so many security features such as being read-only and allowing access to only your own timeline.
I went to great lengths to ensure that private data (such as protected tweets) were not accessible. This is more than the myriad third party widgets for displaying tweets will do out of the box. I imagine these will slowly be shut down too, and I fully expect to see a clause added to Twitter's terms at some point that completely forbids public transmission or display of any content obtained from the Twitter API at all.
This is of course a completely pointless argument, because Twitter has final word on how my service is defined. I've got a living to make, so I'm going to get on with that instead.