It is not an impact on the epic scale of an asteroid smashing into the Earth and killing off the dinosaurs, but the collision of technology and media is having profound effects on a more modern ecosystem.
Media are becoming democratised, and a global conversation is emerging.
The traditional media?
The tools of production - used to create digital content such as blogs, podcasts, wikis, discussions, multiplayer games, mashups (I'll describe each of those in more detail below) - are increasingly powerful and easy to use, yet decreasingly expensive.
Distribution is also becoming less expensive and easily arranged. The internet is a global platform, and the most important one for the future. But mobile-phone networks are part of the overall communications ecosystem, too, and for many on this planet a primary means of contact.
The democratisation of media is also, fundamentally, about the people we once called mere consumers. Their role is evolving from a passive one to something much more interactive, but they are blessed (or cursed, depending on one's viewpoint) with an unprecedented variety of voices and services.
The democratisation of media creation, distribution and access does not necessarily foretell that traditional media are dinosaurs of a new variety. If we are fortunate, we'll end up with a more diverse media ecosystem in which many forms - including the traditional organisations - can thrive. It's fair to say, though, that the challenges to existing businesses will be enormous.
HAVE YOUR SAY
The vast majority of blogs are self-indulgent ramblings
One thing that does surprise me ... is the amount of personal information people are prepared to make available
Tim Dennell, Sheffield UK
For my part, the most exciting aspect of this change is in the emerging conversation. Bottom-up media tools are conversational in nature, even though they can be used in a top-down mode. (It is more accurate, actually, to think of these tools as "edge-in", deployed and used from the edges of networks.)
Let's look at several of the most important tools in today's evolving media sphere.
Blogs, short for weblogs, are getting the most attention, and for good reason. They are all about a web that is "read-write" as opposed to the mostly "read-only" medium of the 1990s.
What is a blog? Nothing more than an online journal in reverse chronological order on the page, that is, where the most recent updates are at the top. They typically have hyperlinks, or web pointers, to other sites. Many blogs also solicit comments from readers.
The most important aspect of a good blog is its humanity
The most important aspect of a good blog is its humanity: It has a distinctly human voice, even if the postings are being done by a group instead of an individual.
Remember: The conversation is an essential part of the process.
A wiki is a website on which anyone can edit any page. This sounds like an anarchy, but it doesn't have to be: the Wikipedia project - an online encyclopedia with more than a million articles in a number of languages - is far from perfect, but it's a remarkably valuable addition to the reference universe.
Wikis may turn out to be most useful inside networks, such as at corporations, where people can work together on project planning and other common interests.
At the University of Hong Kong, where I've taught part-time for the last few years, my co-lecturer and I have gotten excellent results in planning class projects with wikis.
The word "podcast" is a combination of two concepts - broadcasting and the Apple iPod music player.
That's a mistaken word pairing, given that podcasting is about the ability of almost anyone to create audio content that typically has a small audience for any individual program, and then sending it to any digital device, portable or not.
Technology allows media consumers to have more of a say
The actual human voice has its own power over the written word. We get different nuances from audible speech, and they can often tell us things the printed page cannot.
Video podcasts will be the next generation of this genre. But given the difficulty of creating and editing a video that anyone (other, perhaps, than our families) might want to watch, it will probably be some time before this medium takes off. (I may well prove to be wrong about this.)
In Silicon Valley, the current rage is called "web 2.0" - a reference to the web as a computing platform in its own right.
As more and more companies give third parties a way to combine their web-based data and services with other companies' data and services, clever folks are mashing things together in remarkable ways. For example, check out ChicagoCrime.org, which puts government-provided crime data on Google maps and lets people drill down into detail.
Now add to this the idea that everyday folks can start annotating maps and other kinds of information on their own. The possibilities seem endless.
Those are just a few of the concepts in the new world of media.
In coming months, we'll talk about how people inside and outside of the media business are putting these tools to work. We'll also look at some of the difficult policy questions, such as copyright and privacy, that will need resolution. For anyone who cares about the future of media, these are complicated times - and great fun as well.
Dan Gillmor is author of We the Media, a book about technology and the development of grassroots journalism. He is also director of the Center for Citizen Media.
Dan is writing a series of columns for the BBC News website. He will also respond to readers' questions and comments in the week beginning 20 March, in a change to the previously announced schedule.
Do you agree with his views?