Currently our blog lives at http://wikimediasverige.wordpress.com/ but since we pay (to get rid of advertisement) we should qualify for the custom domain name per this table. It would therefore make sense to make the primary domain blogg.wikimedia.se (or possibly blog.wikimedia.se).
This article explains how to map a subdomain.
What we need to investigate is if this will kill all old links to http://wikimediasverige.wordpress.com/
Mapping multiple subdomains (e.g. blogg. and blog.) costs $13 extra per year.
Currently http://blog.wikimedia.org simply redirects to the wordpress