Twitter is a system to perform “micro-blogging”. Like SMS, your posts are limited to 140 characters. A lot of interfaces exists to tweet from laptops, mobile phones, PDAs, … It’s really easy to tweet from everywhere.
According to a post on /., squatting of Twitter IDs will become soon a problem… like every public service in fact! If a platform is used by enough people, it will automagically become a target for malicious activities! Nothing new hélas!