Announced in this post on Google+, the new feature will be built into the core of CyanogenMod for the best possible experience, as well as being available via the Play Store for non CM devices (in addition to planned cross-platform support).
"We are partnering with @Moxie from TextSecure to build this solution. He is building an iOS app [and] also going to be helping out on the Android side to build an Android equivalent into CM, as well as a standalone [app for the] Android Market...We hope that making this cross-platform will make this a lot easier for users to use this seamless messaging." - Koush
"By making this seamless into the framework, this will work regardless of the text messaging application you use, [on CyanogenMod] including all Third party apps". - Cyanogen
I look forward to seeing this in future builds!
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