Cover in their blog post mentioned about this,
We started Cover a year ago because we believed in two things: 1) the untapped potential of the supercomputers we carry in our pockets, and 2) the amazing power of Android. We built a replacement for Android’s default lockscreen that makes our phones easier to use by adapting to our context — providing fast access to the right apps at the right time.
Since launching Cover in October, we’ve had the privilege of reaching hundreds of thousands of people. We’ve improved Cover with their help and feedback, and demonstrated how Android can help make people’s lives easier.
It’s been an incredible journey, a journey that we’re excited to announce is taking a turn today as we bring the Cover team to Twitter to take these ideas even further.
Twitter, like Cover, believes in the incredible potential of Android. They share our vision that smartphones can be a lot smarter — more useful and more contextual — and together we’re going to make that happen. We’ll be building upon a lot of what makes Cover great, and we’re thrilled to create something even better at Twitter.
So what does this mean for the Cover app? For now, Cover will remain available in the Play Store while we focus our attention on our work at Twitter. If that changes down the road, we’ll provide another update here.
Thanks to all of you who beta tested our app, provided feedback, and helped us build Cover into what it is today. We’re excited for this next chapter and can’t wait for you all to try out what’s next.