Good question. Topics will run the gamut of applications of JS (browser, Node.js, Windows 8, etc). We used GitHub to post a public call-for-speakers. Prospective speakers were asked to fork the repo, add their proposal and submit a pull request. All credit to Troy Howard (@thoward37) for setting that up. You can check-out the submissions here:

https://github.com/cascadiajs/cascadiajs.github.com/tree/mas...