With Bluetooth finding its way into an increasing number of devices, a new pastime called 'bluejacking' has popped up. The new fad is to send mischievous messages wirelessly between Bluetooth-enabled phones, and watch the shocked look on the recipient's face. Every Bluetooth phone in range can receive the unexpected, unsolicited message. Recipients are said to be "bluejacked" (a word derived from "Bluetooth" and "hijacked"). Unlike regular SMS text messaging, there is no charge for sending a Bluetooth message and they can be delivered in areas where there is no network coverage. Since Bluetooth-enabled phone, PDAs and Laptops can search for other devices within their short range, bluejackers in crowded transport hubs, pubs or any other public place can easily send messages without being detected.

Recipients must, however, accept the incoming data. As bluejackers are unable to send long messages, they get around this by sending their username as "You have just been Bluejacked!" so that the would-be victim receives a message along the lines of "Incoming message from: 'You have just been Bluejacked.' Would you like to accept?"

Unexpected messages on your mobile may lead you to believe that you are the victim of a new mobile phone virus, or receiving cell phone spam. As these unsolicited messages are being sent by someone in your close vicinity they can also include personal information about your appearance, or your environment, which may alarm you into believing that you are being stalked. Though certainly an annoyance, bluejacking does not pose a security threat and individuals wishing to avoid the aggravation can set their device to "invisible" or can simply shut off Bluetooth when not using it.

Though the ranks of bluejackers remain small, chatter on Internet forums about the hobby has already begun and possibly the first bluejacking Web site has also popped up at www.Bluejack.com.

The Bluetooth protocol enables devices such as mobile phones and laptops to send data to other devices, without wires, over distances of about 30 feet. Introduced as a replacement for cables in 1998, Bluetooth has been slow to gain mass-market penetration, with interoperability and interference problems blamed as the main reasons.

But now the technology can be found in an estimated 100 million devices - from cars and laptops to phones and MP3 players. According to the Bluetooth SIG, the group that promotes and ensures interoperability for the technology it is widely expected to become used by more mainstream consumers in the months ahead.

Bluetooth's growth may not convert bluejacking into anything more than a short-lived fad. But it can really act as a market driver. There is limited room for Bluetooth messaging applications, but other uses of the technology are likely to drive the technology in more meaningful ways. Among the top drivers will be Bluetooth hands-free ear-pieces for mobile users looking to talk on their phone while in the car.

A number of websites have been opened to describe how to bluejack, and the craze is expected to spread. Users who do not wish to receive the messages (which can be a nuisance as they must be deleted) turn off Bluetooth capability when they do not require it.