The news I’ve been waiting to hear is, well, here. Per the CyanogenMod Google Plus page:
“Starting tonight, the 2014 HTC One has been added to our roster of devices receiving nightlies. This device will carry the codename ‘m8’ and be applicable for the following: GSM model, Verizon model, Sprint model”
The free and open-source version of CM has hit nightly status for the metal-clad HTC flagship, and the builds are currently available at the CM downloads site. If you like living on the edge, go ahead and get cracking, but be warned, that as nightly versions there will be issues to work out. CM is usually pretty complete but it’s early days yet. Enjoy!