According to those crazy folks at OnePlus, their first foray into smartphones, the OnePlus One, will be receiving the Android Lollipop update by the end of March. They boasted that if they don't launch the OS by that time-frame then they would give away five 64GB smartphones.
On top of this, they indicated that OnePlus One owners will actually get to choose between the "Lollipop-based OxygenOS ROM, which will get released before or on March 27, and CyanogenMod 12S, which will follow on March 30." OnePlus devs shared that the reason they were late cranking out the latest Android OS was primarily due to important driver updates, an unforeseen OS signing issue, and rebuilding the camera app for compatibility. That seems like a reasonable excuse.
We will keep you posted if/when they meet their deadline.
Source: Android Lollipop Update - Official Release Dates - OnePlus Forums
Here's our dedicated section for the OnePlus One: OnePlus Smartphones Android Forum at DroidForums.net