Unfortunately, to my knowledge, there is no organized archiving of this information. A task for librarians and archivists and historians and news source devotees awaits.
This really is a task that needs to be addressed. After all, many bloggers consider themselves part of a group of new media outlets. Other media outlets are archived, indexed, and infinitely searchable. Who is doing this in the blogosphere? Who is preserving this for future historical reference? Whether or not one believes the hype about bloggers being part of the new independent press, this is a cultural phenomenom that is worth preserving. Fifty years hence, when a student wants to report on societal views and trends, she'll be able to pull up video, newspapers and magazines, audio recordings, and other items. But will she be able to access blogs?