A few people already discussing WordPress + Google Wave ideas.
Could Waves be used for posts, pages and comments/discussion? A tight integration of Google Wave into the WordPress core means a complete re-write of WordPress. So it's just a discussion about far off possibilities for now.
WordPress is meant to be all about "pressing" content out to an audience. Today we all want to "press" more than a 5 paragraph article with embedded photos and videos. We want to press/post anything. Hence the multitude of Tumblr/Posterous like sites around. But we also want to communicate around the content we publish. Hence IntenseDebate, DISQUS and Facebook/Twitter connect.
Because Google Wave is Open Source, it seems like a good candidate for evolving both the communication/publishing side (blogging) but also the social (collaboration/comments/discussion) side in a single core product.