Build 2014 is only a few weeks away, and the world is expecting Microsoft to finally unveil Windows Phone 8.1. The beta SDK is already in some hands, and we’ve even heard some 8.1 hardware is now circulating too for some devs. This is unsurprising, because Microsoft is not going to announce this thing with no release details on April 2. Quite the opposite, as Redmond appears to be taking a “hit the ground running” approach, making the OS preview-update available that day with new hardware only a few weeks later.

In that regard, seeing Microsoft check app compatibility when submitting new XAP files to the Store should not be a shock. After all, they probably want to test some things out, and we’re sure little nuggets like this will make an appearance between now and April 2. The change in the Store happened in the last five days, with people noticing late last week.

The process is simple: access a Windows Phone developer account and go through the rigmarole of submitting an app. During the upload process, developers will see a “Supported OS” section with 8.0 and 8.1 listed. All current apps are expected to be able to be run on Windows Phone 8.1, though apps taking advantage of new 8.1 SDK features won't necessarily work on 8.0 devices.

This is curious as it’s one of the first times Microsoft has referred to the “Spring Update” as 8.1. Granted, we were 99% sure that’s what they were going to call it, even if it’s functionally it’s more like an 8.5 overhaul.

Just file this under ‘interesting’ info, but nothing that directly changes anything we already know. Stay tuned for Build on April 2 in San Francisco, where the Windows Phone Central team will be on hand to deliver all the latest on the Windows Phone 8.1 announcement.

Thanks, atkulp and Q, for the tips!