Matthew Yglesiasis promoting the idea and Atriosis pointing to it.
Apparently, neither Letsgetitdone [Joe Firestone] nor Corrente is to have any credit, but at least the idea is getting out there.Not to mention beowulf (aka Carlos Mucha), whose idea it originally was. As is recognized in the comments there.
Scott Fullwiler was the first economist to promote it publicly afterwards, and to my knowledge is still the only one to do so.
Read it at Corrente
Platinum coin enters the main stream
by coin seigniorage
(h/t Kevin Fathi via email)