By now, we're all familiar with apps for games, social networking, and work and personal productivity tools. But messaging may be poised to take over as the true killer app for mobile communication. By combining elements of text messaging and social networking, these apps provide a quick-fire way for smartphone users to trade everything from brief texts to YouTube clips.

The messenger app Kik reports having 50 million users, with 200,000 new users signing up each day. WhatsApp has been downloaded more than 100 million times from the Google Play store, and is currently the top-paid app in the Apple App Store. Similar apps such as Line, WeChat, Cubie, and KakaoTalk hold prominent positions in international App Stores.

What are the implications of mobile messaging apps for the training industry? These tools enable cheap and easy access to group chat for your communities of practice. And users can do more than exchange a simple text. Most mobile messaging apps allow users to share their photos, videos, and location information.

For instance, Kik introduced "cards" that enable web-based applications such as YouTube viewing and collaborative sketching. Messaging apps already have experimented with advertising and e-commerce. Perhaps learning tools could enter the game.

Not to mention, messaging apps are inexpensive, and they don't charge per message the way text messages do. Simply put, it's a cost-effective way to connect workers so they can learn from one another.