In what could be the clearest indication yet of their growing interest in mobile, Twitter has acquired Crashlytics, the “powerful, yet lightest weight crash reporting solution”, for an undisclosed sum.

This follows the announcement of video-sharing app Vine last week, which launched to some fanfare.

The good news for existing fans of Crashlytics? It looks like Twitter has promised to leave them alone, with the Crashlytics’ blog reporting that development will continue “unabated”.

Of course, we’ve been here before, and Twitter doesn’t exactly have the greatest of “if it ain’t broken” track records. Aside from Twitter and Vine, other important apps currently using the service include those of Yelp, Walmart and Groupon, and it will be interesting to see if and how those relationships change following this announcement, which you can read below.

We started Crashlytics a little over a year ago to address a huge hole in mobile app development. With hundreds of millions of devices in use around the world, it was impossible for developers to fully test every edge-case and catch every bug before release. Even worse, when problems did crop up, it was often difficult and complicated to find the root cause. App developers were stuck with little insight into what happened and forced to rely on vague end-user feedback to diagnose problems.

With today’s announcement, much will remain the same. Development of Crashlytics will continue unabated and we remain dedicated to working with all of our customers – current and new, big and small – to deliver the key app performance insights they need.

Going forward, we’re thrilled to work with the incredible team at Twitter. We share a passion for innovating on mobile and building world-class applications. Joining forces will accelerate our build-out, allowing us to leverage Twitter’s infrastructure to deliver new features faster than ever.

As said, this is a very interesting purchase for Twitter, inasmuch as it’s a pretty clear signal of the micro-blogging network’s interest in the massively-important mobile space, which increasingly appears to be the “One Ring” of social media.