This is supposed to be the month where every OEM who promised the Lollipop OTA within 90 days rolls out that said update.
Lollipop build for @oneplus one has entered QA/QE stage for release! Testing & cert to begin alongside 3rd party partners to meet GMS reqs.
— Cyanogen Inc. (@CyanogenInc) February 1, 2015
According to the Cyanoged Inc., CyanogenMod 12S (made specifically for the OnePlus One) is in its final quality assurance testing phase. However, since its not just Cyanogen involved in this process, this will take a few days to finalize, including getting the update certified for Google Play Services.
The update itself is based off of Android 5.0.2 AOSP and includes all the usual CyanogedMod features you find in CM-based custom ROMs. Alternatively, we learned that OnePlus is developing its own Android-based OS for the phone by the name of Oxygen OS in order to slowly remove their dependance on CM and support users in the long run.