A quick FAQ on what Twitter is. Twitter is a micro-blogging platform where all posts must be 140 characters or less. It basically lets you do quick posts that your friends and family can follow and respond to.
Twitter had allowed you to send in messages via your cell phone but due to some problems it was down for a few weeks (estimated the time). The SMS feature has again been enabled and appears to be working – I dont currently use it but have seen others. So as of now you can use a 3rd party Twitter application, your cell phone, the website, or a instant messenger.