Google had become rather predictable at introducing new major Android releases, announcing two a year, when we most expected them -- around late-June and October. But this changed in 2014. Lollipop stood alone. What's more, the first major update that followed -- version 5.1, which came earlier this year -- arrived completely unannounced. There wasn't even a blog post about it, as we confirmed its existence based on reports from folks who discovered it on their Android One smartphones, and a mention in passing on the Android One site.
Weeks after Android 5.1 was revealed to exist we are still waiting for Google to tell us more -- well, something -- about it, including when we should expect to see it available in the Android Open Source Project. Luckily, we may now know this important detail thanks to an HTC VP.
When asked about an update for HTC One (M7) Google Play Edition, HTC's vice president of Product Management Mo Versi replied on Twitter that "It'll be tied to Google's next MR, which is in March".
In Google speak, MR means Maintenance Release, and, based on what we know so far, there is no other version of Android that could qualify as the next "MR" but Android 5.1 Lollipop. Of course, it could also be Android 5.2 that's coming next month, but it is even less official -- if that's possible -- than the second Lollipop installment.
As I mentioned, there is no official information about the changes packed into Android 5.1 Lollipop, but there is an unofficial changelog that is floating around. XDA Developers has commented around a report from a Reddit user who has one of the Android One devices with Android 5.1 on board, and you can read the major findings here.
Either way, once the next Android MR hits AOSP, it won't be long before enthusiasts come up with updated custom distributions. Google is also fairly quick at rolling out a new release as an over the air update, and posting the factory images.