Moxie Marlinspike is working with them on their implementation of a more secure SMS app[1]. It's based on his previous secure SMS app I believe[2]. While I'm not sure I would use their CM Account¤ (also optional), the source[3] for the website mentioned in the article is up on their Github for anyone to critique. Site repo only appears to be the frontend though.
[1] http://www.cyanogenmod.org/blog/cyanogenmod-account
[2] https://whispersystems.org/
[3] https://github.com/CyanogenMod/CMAccountWebsite
¤ They're using encryption on the front end in JavaScript and that has me a bit worried if that is what they're solely relying on:
https://github.com/CyanogenMod/CMAccountWebsite/tree/master/...
http://www.matasano.com/articles/javascript-cryptography/
http://rdist.root.org/2010/11/29/final-post-on-javascript-cr...
https://news.ycombinator.com/item?id=4549504
https://news.ycombinator.com/item?id=2933730
https://news.ycombinator.com/item?id=2723332
https://news.ycombinator.com/item?id=6354883