This has been happening since at least the late 90's when I started to get involved in open source.

Heck, I've sponsored a number of projects back then as a teenager with a fledgling Internet business - with the express purpose of advertising to highly technical users I wanted to potentially sell to.

I'm not sure if it was terribly effective at sales marketing, but it was highly effective at marketing towards the types of employees I wanted to work with. I see sponsoring open source projects as more of a recruitment thing than sales thing these days.