For anyone interested in technical stuff: php periodically talks to the APIs of YouTube, Flickr and AudioBoo to aggregate any geo-tagged content kidmapper creates; the webpage loads up a Gmap, and retrieves a RSS-like feed of all the content, and some Javascript classes add each item to the map, and display the media in their respective place-holders.
I did spend some time trying to make the mashup in Flash, but had so much trouble loading and unloading YouTube movies in AS3 that I nearly wept blood; afer that, building it in JS, which I often find knuckle-tearingly frustrating across browsers, was actually a comparatively joyful experience. Yay!
Tim Wright's Kidmapped! journey has resumed and I've built a little mash-up of the mapped media he's made as he travels the route of Robert Louis Stevenson's classic novel. Check out Kidmapper's blog, youtube, flickr, audioboo, podcasts, twitter and of course, the mashup.