Mine would be slightly less than 10% by 2030, slightly greater than 85% by 2080 conditional on a general continuity of our civilization between now and 2080, most likely method of origination depends on how far we look out. More brain inspired methods tend to come later and to be more likely absolutely.

We at SIAI have been working on building a mathematical model of this since summer 2008. See Michael Anissimov's blog post at http://www.acceleratingfuture.com/michael/blog/2009/02/the-uncertain-future-simple-ai-self-improvement-models/. You (or anyone else reading this) can contact us at uncertainfuture@intelligence.org if you're interested in helping us test the model.