'Chalkbot' tweets the streets of the Tour de France

Anyone who's watched coverage of the grueling mountain stages of the Tour de France has seen them – the messages of support painted on the roads ahead of the race. This year they've taken a decidedly techie turn.

A collaboration between Lance Armstrong's LIVESTRONG foundation and Nike has brought about "Chalkbot," a robot that paints messages of support submitted by the public on the Tour's roads in water-soluble (and biodegradable soy-based) yellow paint. Armstrong, a seven-time Tour de France champion, has said that his main motivation for returning to professional cycling was to raise cancer awareness.

The rig used in the campaign, developed by Pittsburgh-based mobile software company Deeplocal and Standard Robot, is a similar concept to what "Bikes Against Bush" creator Joshua Kinberg used (and was arrested for) at the 2004 Republican National Convention in New York. Mr. Kinsberg's bike-mounted rig used cans of water-soluble paint to write messages sent from the Web on the streets of New York. Each message was geotagged, and a built-in digital camera sent pictures of the message to its submitter.

Chalkbot works much the same way – only it's towed by a truck, not a bike (I'm not the only one disappointed by this.) Messages are photographed as they're painted, and a picture and GPS coordinates are sent to the message's submitter. The device is towed at 5 m.p.h., and was painting 200 messages a day at the start of the Tour, Deeplocal CEO Nathan Martin told CNN.

To add your message, hop on Twitter and post a tweet to @chalkbot followed by the #LIVESTRONG hashtag. By SMS, text LIVESTRONG followed by your message to 36453. Or, submit a message on the Web, here.

The Livestrong Foundation was cited in a Mashable post last month for how it uses social media for good. It's worth a read.

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