Not too long ago, it was made official that Lumia Black update is rolling out globally for all Lumia devices. The update has already hit Lumia 1020, 925, 920 and 820 in most of the regions, while Nokia Lumia 1320 and Lumia 1520 come pre-installed with Lumia Black update. Now, it's rolling out for the low-end line up starting with the Nokia Lumia 625, which might be kind of surprising as Lumia 520 has the highest market share when it comes to Windows Phone.
It's not just the SIM-free variant that received the update, even some of the carrier-locked models also got the taste of the Lumia Black update. For instance, Lumia 625 tied to Singtel received the update, along with some carriers in Australia, and Europe as well. The Nokia support page lists Lumia Black update as "available" for a majority of regions while others list it as waiting for approval. You can also check from the support page if the update is rolling out for your country and device.
The latest Lumia Black update with Windows Phone 8 GDR3 on top of it introduces several new features and enhancements, including screen orientation lock, glance screen, custom ringtones for various applications such as email, messaging, Nokia Camera app, Bluetooth LE, driving mode that restricts notifications while driving, Nokia StoryTeller, Nokia Beamer application (also supports other Lumia devices with 1GB of RAM), improved storage management and WiFi sharing, and more. It's also worth noting that users may not get to enjoy all the listed features in the Lumia Black update on Lumia 625 due to hardware limitations, as some of the features and applications requires more RAM.
The update process is gradual and it may take some time for it to reach your device. If you don't want to wait, you can manually check for the update by navigating to Settings > Phone Update. Let us know in the comments below if you received the update, along with your region.