Posers can become performers with a high-tech T-shirt that turns the strumming of an air guitar into music.

Motion sensors built into the shirt’s elbows pick up the wearer’s arm motions and relay them wirelessly to a computer that interprets them as guitar rifts, said Richard Helmer, an engineer who leads the research team from the Australian government’s Commonwealth Scientific and Industrial Research Organization.

Helmer, a 34-year-old part-time guitarist with several bands, said Wednesday he did much of the development at home as “a more fun product” that built on research the CSIRO conducted into monitoring the knee movements of professional soccer players.

With strong interest in the “wearable instrument shirt” since the prototype was revealed Monday, Helmer is considering going into commercial production soon.

Helmer said he could add gloves to interpret the would-be rockers’ finger movements, but that would prove too challenging for the musical skills of most air guitarists.

AOL is catching up: AOL’s new instant-messaging software adds offline and logging capabilities already available with rival programs.

Yahoo Inc.’s Messenger and Microsoft Corp.’s Windows Live Messenger let users send messages to friends and other contacts who aren’t online. Recipients then get the messages the next time the log on. Time Warner Inc.’s AOL adds that feature in AIM 6.0.

Also with Wednesday’s launch of AIM 6.0, the three major services – all free – now offer the option of automatically saving chat sessions.

Microsoft’s installs with the “off” button initially selected, while Yahoo’s automatically records chats but clears them when a user signs off. Yahoo users can choose to turn it off or to record forever.

Battery recharging device is all in his head: There may be hope – however distant – for recharging nearly drained cell phone, laptop and other batteries without plugging them into the wall, a scientist said.

Although he hasn’t built a device yet, Massachusetts Institute of Technology physics professor Marin Soljacic said he has figured out how to wirelessly recharge batteries, much like the way people can surf the Web untethered.

In a presentation Tuesday at an American Institute of Physics forum in San Francisco, Soljacic made the case for using specially tuned waves of electromagnetism that don’t radiate like normal waves.

The idea is that the recharge device and the receiver would be on the same acoustic frequency, similar to how a radio picks up only one channel at a time, so that the energy would mostly go straight to the intended battery, Soljacic said.

Some of the electromagnetic energy would go elsewhere but Sojacic doesn’t believe it would harm people, noting that humans can endure strong magnetic fields with magnetic resonance imaging machines.

Soljacic envisions a device with wiring loops mounted on the ceiling of a room. He even sees this as a way of recharging electric buses on the go if there’s a large “pipe” with recharging energy above a highway.

Redesigned MP3.com is back on line: MP3.com is reopening its servers, nearly a decade after it helped usher in the online music era by letting largely unknown bands submit files for computer users to download.

The site, acquired by San Francisco-based CNET Networks Inc. in 2003, has recently undergone a redesign. Relaunched officially on Tuesday, the site now offers up to 100 megabytes of storage space for audio tracks and unlimited space for videos, free of charge.

The company won’t say how many independent artists or tracks have been uploaded to the site since it began accepting files a few weeks ago.

CNET only bought the Internet domain, not the library of more than 1 million tracks that bands had uploaded to MP3.com since 1998.

So, until recently, the site focused on offering editorial content on major label artists and enabled visitors to stream select tracks and videos while online, typically with links to Internet music stores where fans could buy downloads for portable devices and offline play.

The revamped site weaves in tracks and videos by independent and unsigned bands for visitors to download directly from MP3.com.

Be wary of terrorist recruiting efforts: Terrorists who have long embraced the Internet for propaganda and planning have begun to post comedy and Top 10 lists to draw in young recruits, experts say.

Bouchaib Silm, a researcher with the terrorism department at Singapore’s Institute of Defense and Strategic Studies, said Web sites are becoming more modern in design, incorporating content designed to hook a younger generation of sympathizers and potential recruits.

Sites can no longer simply show videos of Osama bin Laden giving an hourlong speech as he sits in front of a bare wall, Silm said.