WordPress itself is not architected in MVC, but one can build very MVC oriented themes and plugins within the framework. There are several tools which can help:
WordPress MVC solutions:
- Churro: @ wordpress.org/extend/plugins/churro
- Tina-MVC: @ wordpress.org/extend/plugins/tina-mvc
- Plugin Factory: @ wordpress.org/extend/plugins/plugin-factory
- MVCPress: http://mozey.wordpress.com/2007/01/22/mvcpress-screenshots/#comment-3634 (abandoned, but interesting ideas)
MVC threads on WordPress.org Ideas and Trac:
- http://wordpress.org/extend/ideas/topic/mvc-plugin-framework
- http://wordpress.org/extend/ideas/topic/complete-reestructuring
- http://wordpress.org/extend/ideas/topic/rewrite-wordpress-using-mvc
- http://wordpress.org/extend/ideas/topic/wordpress-theme-revamp (more on XSL than MVC)
- http://core.trac.wordpress.org/ticket/12354 (on MVC in widgets)