The name "IMX214" might not be very familiar if you're not a Chinese smartphone enthusiast, but for those of us who are, it represents the "gold standard" of mid-range cameras. These cameras are found in every other phone from every other manufacturer, popular for having a very reasonable f/2.0 aperture and producing some wonderfully crisp photos in the right type of lighting. The camera is also found in some more mainstream phones, such as the Nexus 6 and the OnePlus One.
The problem appears that this specific camera has become too popular. Driving the issue is the recent price drop of the camera: being "last-gen," Sony dropped the price enough to make it attractive to the low-cost smartphone manufacturers, but unfortunately, it seems the tactic has been overly successful. Reports are indicating that Sony is experiencing such a significant backlog that only 50% of the orders will be able to be fulfilled.
If the report is to be believed, then this will force smartphone manufacturers to either delay shipping out their product, artificially limit its availability, go for another Sony camera or drop the dependence on Sony altogether for another low-priced alternative from a rival company like Samsung or Omnivision - the latter of which may be a good decision. Although the name doesn't have the brand power of Samsung or Sony, it still produces some of the best cameras on the market.
There may be some truth to the report, as just a few days ago we saw Elephone - the company behind the Pioneer P7000 - report that batches of their pre-ordered P7000 smartphones will be shipped with a different camera due to the shortage. Eventually they reneged on the decision based on popular demand, but they still emphasized that the camera really is in short supply.