Semantic Mediawiki compared with Drupal and content management systems
The distinction is in the capability, and the phrase 'community plumbing.'
When developing a functional web site, once we get into the php / database level, things get tremendously more complex. Semantic Mediawiki avoids that altogether by building on Mediawiki markup and a higher level of expression.
The Drupal core developers have a policy of not maintaining backward compatibility between major versions. So a client with a Drupal 5.x module has a real problem. If something goes wrong or needs to be changed/extended on a module, you have to find a developer willing to do that work, which is very specific. They may need to update to the latest Drupal, which is a major undertaking when all modules are considered. Any change on a Drupal site, no matter how minor, might involve dozens of hours, it involves accessing the server via ssh or ftp, changing the database, you name it. It's clearly out of the hands of mere mortals. I saw this again and again, and was forced to create this situation. I see a lot of programming shops that have bad relationships with their clients and act very defensively, with high charges for every change, because of the complexity involved.
Whereas with SMW, you can view the source of any page to see how something was done, and do it yourself.
Granted, SMW is not a full programming system and can't do everything php/Drupal can do, but it can cover a large number of cases - blogs, discussions, home pages, events, hypertext pages, database functions including locations, dates, etc.
Many non programmers edit Wikis, none can change a Drupal site. They're completely reliant on the plumber. The plumber has to chose a particular version of Drupal for particular modules, which is probably not the most recent version so it has built in obsolescence. If the client can't reach their original plumber, they better hope they can find someone who can deal with the previous work. SMW has core underpinnings, with markup on top of that, and it's all built on the thousands of tested MW modules.
People can progressively learn MW/SMW, they really can't do that with Drupal without creating a disaster. I've taught non technical people to create schemas, queries and views in SMW. They typically didn't use the advanced function after the overview, but at least I'm teaching them more than how to fill in a form, and the computer isn't so much a scary database and mystical programming language, it's clear it's a participatory medium built on the momentum of Wikipedia. There's no similar heralded Drupal site (Drupal was used for the Howard Dean campaign, but any CMS could have been used).
I don't know much about Wordpress, from what I understand it's more something you use as is, the customization is more around themes. Last I checked, Drupal was heading in a more fluid direction with CCK (with RDF under the covers for reusable content across sites), but it's still not the same thing as the "aliveness" of an SMW page. If I could cc this message to an SMW install (extensions exist for this), I could create todo events, pages, entities, all using the established MW/SMW combo from email.
My interest is in digital literacy.. getting people to stop using computers as fancy typewriters, instead create reusable statements, schemas, queries, progressively build on their knowledge in focused ways, always able to learn from examples. SMW excels at that. Any content on an SMW site can be reused between functions, and sites can access each other's information.
MW/SMW also comes with a culture of Creative Commons style licenses. On a MW/SMW site, any user can create their own sub site out of pages and structure, and take it away if they need to. On a Drupal site, it's all top down.
I try to get this across to clients, ultimately they usually enjoy the overview but can't participate for their own good reasons, which is fine. SMW isn't ready for everything yet, but I think the markup approach is the best way out of MS Word / forms based approaches.
See also: SMW as Lego blocks