I feel like a spectator admiring athletes reading things like the this blog post [Semantic Wikipedia - At last one of dreams is at the verge of coming true.], but an excited spectator, none the less.
Wiki is already a fantastic tool for simple (or complex) content management, accessible to anyone within a few minutes… This proposed innovation would add the ability to add, inline, extra relationships which build a more complete (and interoperable) logical structure.
IMO – one of a Wiki’s strongest points has been how free form and structureless the system is – so you can do whatever you want with it…. but, there are downsides to a semi-structured system, specifically for accessibility and user understanding (overviews).
Enter: Semantic Markup
For more information on it, I strongly recommend you read the aforementioned blog post and the Semantic MediaWiki/Implementation talk page.