Luckily, Jacob Briars, currently the global brand director for Leblon cachaca (and formerly with 42Below vodka), sent me an email with the full story as he remembers it.
You are right, like so many great bartending tricks it has its genesis south of the equator, in early 2006 as I recall, maybe even earlier. As far as I understand it, here is the potted history of 'dust':
Many bartenders will have noticed that spirits that are high in sugar will often crystallize around the mouth of the bottle – Campari, Frangelico and Chartreuse are particularly prone. (Campari's dirty secret is that its inherent bitterness masks an insane amount of sugar that would shame most liqueurs)
The first person I know of who thought of a cocktail application for this was Mick Formosa, who used to run the bar at Ginger in Melbourne, 2005-2007. Previous alumni of this place include Sam Ross, Sebastian Reaburn and Jason Williams, and in the mid 00s it could have made a good claim to be one of the best bars on earth. Sadly the recession saw the end of Ginger and it closed 2 1/2 years ago.
Anyway, I digress. As I understand, Mick was cleaning the bottles as per usual one Sunday night and noticed the Campari crystals, and tried tasting them. He immediately thought of the possibility of using these in a drink, and texted a similarly adventurous bartender, Sydney-based Ben Walsh, who was running the superb Victoria Room. Ben set about trying to produce Campari dust on a bigger scale, using a roasting pan in a barely heated oven (from memory he used the pilot light in a commercial gas oven, which was more than enough heat) until dehydrated, then grinding the dried Campari into a powder using a mortar and pestle. Between two great bartenders in two great bartending cities, this technique caught on quickly.
Later that year (2006) it saw its first major public outing when flavored 'dust' was used by the Australian team at the 42BELOW Cocktail World Cup as a sugar to make a flavored candy floss (called fairy floss in Aust, and I think it's called Cotton Candy in the US?) This application – using various dusts to create powerfully flavored 'boozy cotton candy' also swept across both Australia and New Zealand, but it always seemed to work best with the bittersweet Campari. Floss made with things like Cointreau just ended up tasting like orange.
In 2007, again at the 42BELOW World Cup, another Australian team made a 'dust' out of Chartreuse, and used it to rim the glass for their cocktail and also as a garnish. In that year, the judges included Dale DeGroff, Angus Winchester, and Colin Field (Ritz, Paris) and all took this technique back with them, where it eventually started to be talked about in the US, Europe and the UK.
I've had lots of dusts in NZ and Australia and made many more myself, but none is ever as good as that Chartreuse dust (55% abv Green, btw) that I saw in that comp. Possibly the only use of a 'spirit gimmick' that tastes better than the spirit itself.
I think for this to work, the base flavor needs to be both powerful and memorable. So flavors that can be mistaken for something else in a cocktail, e.g. orange liqueur dust just tastes like orange peel, don't seem to be effective. But liqueurs that are high in sugar, with a striking visual appearance and taste profile, are perfect for this technique. Hence, Campari, Chartreuse, Fernet Branca, are about the best bets. And tho the taste isn't all that unique, color-wise Cheery Heering and blue curaçao will also work well.
Anyway, great piece and I look forward to seeing this develop.
I figure, why not try the method that looks easiest first, even if it seems doomed to fail? 
