While there's still no official announcement as of yet from BlackBerry, the forums are filling up with folks from around the world letting us know that BlackBerry 10.2.1 has arrived on their devices. There doesn't appear to be any rhyme or reason to the release other than that it's happening across several devices and several carriers. Bell, Rogers, TELUS, Virgin, T-Mobile UK, T-Mobile Germany, Airtel India, Mobiliy and more are showing as available.
So, needless to say if you have a BlackBerry 10 device, go ahead and check for updates. Let us know in the comments what carrier you're on and where you live. For the most part, everyone should be seeing 10.2.1.537 as available. While you guys do that, we'll see if we can get a more formal announcement from BlackBerry along with a full list of carriers confirmed to be rolling it out.