Sponsorware

This is a very interesting model to monetize open source and it's not limited to that. It could be used for ebooks, courses, videos, art... anything, really.

The fact that they open it up to everyone once the desired sponsorship goal is reached is a nice touch provided it doesn't make sponsors who paid feel shortchanged.

One way to prevent that is by acknowledging sponsors upon release. The other way, somewhat naturally occurring in most cases, is the delay required to achieve the target number of sponsors.

Generally, I like it.