Open source version of Alpha? That will never happen. Wolfram is the most anti-source-code person out there. He even has this diatribe about why you should not be allowed to see "his" source code:
I don't know if it's too late for this, but as a matter of marketing, why not Omega instead of Gamma? Alpha was the first word on the subject. Omega will be the last.
That's odd for a business so concerned about selling to academia. You'd expect journals to reject papers where the number-crunching went through a "black box" like that.
He mostly claims other people's work for himself. I suppose he's a good salesman and a good huckster, that much is demonstrably true. He's also apparently competent as a mathematician somewhat, but it's doubtful how much of Mathematica really is his own work. He puts everything under his own name and sues anyone who disputes otherwise.
http://www.sympygamma.com
The biggest missing piece it's missing is the data used by Alpha. It's missing other things as well, but it's a start.