My Harvard colleague Persephone Miel unveiled the results of months of labor (hers and her associates’) today: an in-depth evaluation of how far along “participatory media” — bloggers, citizen journalists, et cetera — are in complementing (or replacing) traditional Big Media. Her answer, if I may sum up 168 pages in a sentence: It’s just not there yet. Maybe some day. (I think she’s dead on.)

If you want more than a sentence but less than 168 pages, here’s how she summarizes her findings:

Participatory media is great, has lots of potential. But it’s not doing everything we have counted on journalism institutions to do and, left to its own devices, it never will. Those journalism institutions, never perfect, are in serious trouble. Many will save themselves, as businesses, but there is no guarantee they will maintain their commitment to doing the journalism we need. People who for whatever reason (time, money, skills, desire) are not taking charge of creating their own online news diet still deserve to have access to comprehensive credible sources of news.

The U.S. media system was not handed down from the heavens on tablets. It’s time to look at models from other countries — stronger public media, newspapers less dependent on advertising, etc. We do a lot of studying of online activity, but we don’t know nearly enough about how real people in the real world take in information from many sources and what that means for how journalism in the public interest needs to evolve. We, the people who care about the public getting the information it needs, must take the best from both worlds to build the media we need.

There’s lots more in the various sections of the study, including case studies of several new-media startups. We’ll have more tomorrow, but start digging into the findings today.