The trouble, of course, is not so much the code, but in the training. The best speech recognition code isn't going to be competitive unless it has been trained with about as many millions of hours of example speech as the closed engines from Apple, Google and so forth have been. How can we do that? The same problem exists with AI. There's plenty of open-source AI code, but how good is it unless it gets training and retraining with gigantic data sets?
And even with that data, Siri gets trained with a massive farm of GPUs running 24/7 -- but how can the open source community replicate that? "Who has a plan, and where can I sign up to it?" asks jernst. So leave your best answers in the comments. Who's building the open source version of Siri?