A couple of weeks ago when TechCrunch was in Berlin, we sniffed out and eventually published the details of an interesting investment for a local startup: 6Wunderkinder, maker of the task-management app Wunderlist, had closed a Series B investment led by California’s Sequoia Capital with participation from existing investors Earlybird and Atomico. Now, we have the official details of that news: it’s a $19 million round, and Wunderlist, which now has 6 million people and 50,000 businesses making to-do lists, will be using it to fuel big ambitions: to build out its presence in the U.S. and to turbo-charge Wunderlist – or, as co-founder and CEO Christian Reber told me earlier, “To turn our product into a platform.”

This takes the total invested in the startup to $30 million.

This is a significant investment on another level, too. It represents Sequoia’s first investment in a German startup, and it comes at a key time for Berlin. The city has been hailed by many as the new hotbed for tech startups in Europe, fuelled by a low cost of living, a young and educated population, and a burst of creativity converging on the city from around the rest of the continent. Until now, the city has seen investment and startup activity concentrated among early-stage startups, specifically you venture outside the walls of the Samwer Brothers’ Rocket Internet e-commerce empire.

The next focus product-wise for Wunderlist will be to complete and release Wunderlist 3, Reber says, likely in January/early February. The app – which will go live across all the existing platforms of iOS, Android, Windows, Kindle and web, with Windows Phone still in the works – will include more real-time sharing and collaboration features to build out its premium Pro product. And soon after that, the company will launch an API and develop partnerships with other companies.

The aim here will be two-fold. First, the API will mean that developers will be able to incorporate Wunderlist functionality into their own services – for example, if you read about an interesting event, you can then “Wunderlist” it by clicking on a button, similar to how you pin on Pinterest or post to Facebook and Twitter today.

Second, partnerships will mean that Wunderlist will be able to give users a much more dynamic experience. Say you are making a list of movies that you would like to see on the app. If Wunderlist integrates with IMDb, it could provide you with information about those films; or it can integrate with Moviefone or TimeOut to alert you to where it is playing on a big screen – an even cooler feature when you consider non-blockbuster films that may be appearing for short runs in art house cinemas, where you might miss them playing otherwise. You might even be able to buy tickets to those showings, or to link to them for streaming.

“We want to make lists more intelligent,” Reber says. “That’s very much something that we are thinking about right now.” Considering that the company has as its CTO Chad Fowler, who it hired away from LivingSocial, you can see where integrating interesting commercial content is not far outside of the company’s abilities or sensibilities. This is expected sometime in Q1 or Q2, Reber says.

For Sequoia, rather than a sea-change in strategy, the investment in Wunderlist signifies how the company is continuing to expand in particular areas such as looking beyond Silicon Valley for interesting deals, and in particular product areas.

“The tech landscape in Berlin in Germany is still emerging,” Michael Moritz, the storied investor and chairman of Sequoia Capital, who led the investment in 6Wunderkinder, told me in an interview. “Twenty years ago we would have never dreamed of investing in Berlin.”

He pointed out that this is part of a growing globalization in how interesting ideas are getting hatched in the tech world, which has led also to Sequoia’s growing interest in them.

The company already has offices in China, India and Israel; that is the track record on which the company’s interest in Europe is building as it continues to expand outside the Valley.

“Investing in Internet-related companies is a global undertaking,” he said. Interestingly, though, for Sequoia Capital in Silicon Valley, while the ideas may come from different places, the prize remains Western and U.S. traction. “If an interesting idea is concocted in Menlo Park or Lisbon or Berlin or Stockholm, and it has merit, it is reasonably easy to get distribution in the western world. The challenge really is around being able to recruit people. There are lots of incredibly gifted engineers and others – probably more outside the U.S. than inside.”

So why the interest in Wunderlist? There are, after all, a number of task-managing apps already out there. Moritz points to three areas that caught his attention (startups: take note!).

The first is that combination of solving an essential issue – organizing your time – along with the creation of an app that has pulled off solving it with enough simplicity to be useful today, and to grow in the future. “Organizing tasks is one of those mundane problems that you don’t think of solving until you do,” he said simply. “Any designers that have come up with the elegant simplicity that underlies the Wunderlist product clearly deserve attention.”

The second thing with Wunderlist, he notes (and as I pointed out the other week), is that the app has had extremely strong engagement. “It is part of users’ rituals, as regular as an inbox,” he said. “The frequency of usage is a fabulous building block for establishing a good company.” Wunderlist says it has seen a 476 percent increase in daily activity from its users in the last year.

The third area has to do with the cloud. “Cloud-based applications is an area that Sequoia has liked for several years, and we see 6Wunderkinder as a continuation of the investment interest that first led us to Dropbox and then to Evernote and now to 6Wunderkinder.” Indeed, this fits in with Reber’s own concept of the app as part of a “triangle” of essential apps for managing your life. (Not competing with, but complementing each other – although following that analogy, you have to wonder which one of these may be the “top” of the triangle; perhaps it will be different for different users.)

As for Wunderlist, Reber says that it’s likely that the U.S. expansion will happen in January, with the company now in the process of hiring people in areas like business development to fill that out. Reber will split his time between the two countries. As we wrote before, the company will keep its engineering operation in Berlin.