Microsoft removes the yearly fee for developers
No doubt, this is an attempt to encourage more developers to flock to the platform and add to its apps, since WP's store is well behind the competition – with Apple's App Store and Google's Play Store having around 1.3 million apps each, Windows Phone store lags behind with just 300,000 offerings.
Whether this will have a positive effect remains to be seen. It will attract some developers, sure, but one might wonder what quality of work they will bring. Also – now that developer accounts and apps do not require a fee and will stay online for an indefinite period – will the un-supported apps just linger? That'd definitely be an annoyance, as it's one of Android users' main gripes with the Play Store as well.