Blogs are likewise interesting only because they are RSS feeds so you should put RSS feeds (which are also available automatically from mediawiki to track page-”related changes” or overall “recent changes”, or even particular user contributions to a given wiki) at the centre, not the “weblog” as such. A “trackback” is just an unfortunate term for a stable URI such as major public wikis (like WIkipedia) already enforce, so I suggest you generalize this notion as well into something that fits the terms a serious study would recognize. For instance a stable URI is meritous in many other applications than blogs, and seems to have been the key to Wikipedia’s success. There were always better wikis for any given subject, but it was Wikipedia’s simple standard URI “en.wikipedia.org/wiki/…NAME…” that put it at the core of people’s reference habits.

Mail is also increasingly integrated with other web-based services (witness gmail, yahoogroups) so you may have to draw some explicit line between private, shared, and public discourse. Newsgroups are usually wholly public, mail usually assumed private, but there are exceptions, so deal with this dimension somehow in a way that isn’t tied to the media itself. I think you need also to distinguish between forwarding, “quoting” or otherwise just reposting something, vs. “citing” it as a credible “source” (as one might do for a newspaper article or firsthand report). You might want to look at the issue/position/argument form, which is easy to find references on.

Finally you don’t deal with chat (IRC, “IM”, jabber, etc.) at all nor the concept of logs for teleconferences or other phone logs. I think this is a mistake as these media are getting important. In the long run they will often be attached to specific (internal or external) wiki articles, being debates about them, so I suggest you deal with them as a subclass of conversations about pages if you want to remain content-focused in your ontology.

Compliments for taking it on. It’s a good start, good enough to criticize. but I wouldn’t be writing any software based on it just yet.

I’m not sure I completely agree with the structure. It’s cool to see SKOS used though. There is a meta category which are Post, in this category there are sub-categories entries (ones made by the weblog authors), comments (made by the authors or readers), trackbacks (made by readers). These are three type of posts on a weblog but a comment is not a subcategory of an entry IMHO.