I don't know of any specific efforts to create an open alternative to Siri, but there are a number of speech-to-text translators and natural-language processors

I don't know of any specific efforts to create an open alternative to Siri, but there are a number of speech-to-text translators and natural-language processors that could be combined to do something similar. There are a number of sites dedicated to aggregating making data openly available on github (https://github.com/caesar0301/awesome-public-datasets https://github.com/caesar0301/awesome-public-datasets), but projects such as Academic Torrents (http://academictorrents.com/ http://academictorrents.com/) and Dat (http://dat-data.com/ http://dat-data.com/) are also making strides in openly sharing data. Scaling is probably the biggest issue that you've pointed out, but efforts like BIONIC (http://boinc.berkeley.edu/ http://boinc.berkeley.edu/) allow community members to donate their computing power to projects that they wish to support. Ethereum (https://www.ethereum.org/ https://www.ethereum.org/) also has potential in this area, but given that the network is mostly centered around distributed consensus, it would be more efficient to use a normal computer in this area.