One story I've encountered this week is the release of Soundless by Richelle Mead; I saw people talking about it on my Twitter timeline, and I would consider this as an example of transmedia.
As a book blogger, I am aware that many bloggers/people/authors/publishers promote on various social media websites, such as Twitter or Facebook, where the author of the book can interact with the audience, and where the audience can discuss and spread the topic at hand to a larger audience, by spreading it to their friends and who's friends will spread it to there's etc, in a large ripple affect.
I have experience with transmedia, both in school and in real life. I experience transmedia when I'm blogging, or when I'm watching a television show, and then go online to participate in a discussion or conversation, or watch a video to promote something I watch or heard. The best example of transmedia in my life at the moment is working with my creative processes group to promote our PSA to our demographic using videos, social media, and games/apps.