semsol provides both open-source and commercial solutions:
ARC
Our core RDF toolkit, written in
PHP, and optimized for standard Web environments.
Trice
Trice is a SemWeb development framework that extends ARC2 with an MVC-like layer, forms, templates, publishing tools, themes, and various other goodies. Trice will be made available in 2008, most of the initial modules are production-ready, we'd just like to test things a little more. (The ARC website is one example for a Trice-powered app, it uses the Wiki/CMS module and SPARQL-driven bots for IRC and Mail Subscriptions).
Grawiki
Grawiki combines the ease of Wiki editing with the power of structured Web Data (a.k.a.
Linked Data).
