Twitter is a microblogging service. Twitter is a proprietary software controlled by a company. This means they can kick you if they don’t like your posts or activity on their service. They will sell your posts and control them. They give away the user data and log files to the FBI or everyone who will pay for this data. They can lock their API for you. It is not clever to build a business model on a proprietary software, because they can kick you whenever they want.
The open source alternative for Twitter is identi.ca. It has a compatible API. This means every script or software written for the Twitter-API can run on identi.ca too. You only have to change the URI to the API. Open Source means there are no back doors in the software and no surveillance technique is included.
identi.ca runs in Canada and uses log files to stop Spam. The police can check this log files. They must delete posts, which are against Canadian law.
If you want a very secure microblogging service, you have to install the software on your on server and disable the log files.
Here is a short instruction to identi.ca
You can use tags: #anonymous
You can write to other users: @anonymous