As mentioned last week, Twitter has now launched a new mobile tracking feature.

Users are able to subscribe to alerts based on keywords, for example a subscription for “NYC” will result in a user receiving copies of all tweets that mention NYC.

To turn the tracking service on users should IM or TXT “Track search term”. From there users can IM “whois username” to find out more about that person, or “follow username” to follow all that users updates. To turn the feature off, users simply IM/ TXT “untrack search term.”