I am pondering the process of migrating this system to Wordpress and am using this post as a place to maintain links to possible solutions. I welcome feedback on migration from any reader.

Paid service -- http://worth2read.org/blog/2009/01/31/import-from-b2evolution246-to-wordpress-27/

Seemingly good option courtesy of Wordpress forums -- http://wordpress.org/support/topic/215389

A bit more thorough write up of the process at the WP forums -- http://www.seo-strategies.org/2009/10/migrating-b2evolution-to-wordpress/