This is a very popular social platform for investors and traders. It used to sit on the Twitter platform, but they have since moved onto their own infrastructure. Authentication is OAuth 2.0. As it's a "Twitter-esque" platform, the API provides similar functionality.
http://stocktwits.com/developers

So is anyone planning on writing a API for this platform or does one exist anywhere?

If not, I'm happy to get the ball rolling. I just need to post status updates, so I'm happy to set up a github project for it with the very simplest API functionality implemented according to my own needs. I don't think it will take very long, it'll mostly be a copy and paste of another OAuth 2.0 provider (Facebook) with similar timeline operations to the Twitter API. Obviously it'll all be under the ASL v2.0 and I'm more than happy for someone else to take ownership of it once in place.

Any guidelines for me on setting this up?

Tim