HTC has placed more than a few of their apps onto the Play Store for download by users, much like Motorola has done with a handful of their own apps as well. HTC's latest app to hit the Play Store is their internet browser application that's baked into the Sense UI, so now anyone that uses an HTC device and commonly uses the HTC browser over Chrome or any others, have the ability to receive improvement updates to the app as well as any new enhancements or features that come along when HTC has them ready to go.
Typically with this kind of stuff it's more of a way for the OEM to get updates to users rather than put their software out there for everyone, as this is still limited to usage on an HTC device. I for example cannot install this on my Sony Xperia Z3. That shouldn't surprise anyone though as HTC has no reason to want to give their software based apps up to other users who aren't invested in their hardware. Sony, Motorola, and Samsung all do the same thing with most of their apps too, so this is nothing new and unusual.
For those running an HTC device, waiting for HTC to push out a bigger and more complex software update for the device no longer has to be the same time you get updates to HTC's Sense UI based apps like the internet browser. The internet browser should be live in the Play Store as of this very moment, and this will make it much easier the next time HTC needs to either fix a few bugs with the app, or push out new features to users. As of now with this Play Store release, there are a few new tweaks but it doesn't seem to be anything major. The changes include Text Reflow which allows the text to be wrapped and fit the width of the screen, making it easier to browse when you zoom in or out. There's also a "read later" feature now so users can save articles for offline reading or simply in case they just need to save articles for a later time when they're able to read it. HTC has also redesigned the interface to make the browser easier to read.