As far as I know The Economist coined Billanthropy late June 2006. This may well have been the first time its Scottish founder James Wilson cheered for a decade or two.

WC.TV June 06
Track megatrends from a google of Billanthropy and google news; ... track trends & news of Africa Progress Panel (APP), one of the first experimental "babes" funded by Billanthropy

WC.TV Sept 06
I am beginning to believe that the greatest contributions the Gates' make are behind the scenes which is perhaps the only way that billanthropy can work

For example, Bill Gates was in New York last week at the ClintonGI but he might have been travelling incognito when you rate how little publicity he got this time compared with the trip to New York to celebrate the marriage with Buffett

Equally news is quietly webbing around the world service (London Guardian Sept25, google.org minute 40 sec 25 a few months ago) that one of the greatest innovations funded by the Gates' is revolutionising the pharma industry from the inside with that greatest of systemic innovations the not for profit pharma company