ngallagher's dashboard

Yes! The best way to do that is to go to a domain registrar like Yahoo! http://smallbusiness.yahoo.com/domains/ and sign up for the domain name you want. Then return to your wiki, and upgrade to a premium plan which includes 'Custom Domain Name' support. Then you can associate that domain name with your wiki by following the steps shown here: http://domaindemo.pbwiki.com/

There are all sorts of ways to use this feature - we have corporations using 'wiki.companyname.com' for internal work and non-corporate groups like churches using it as well. One of our largest wikis - http://barcamp.org/ - uses a custom domain. Also check out http://apidoc.digg.com/ - they've combined the 'Custom CSS' feature with a custom domain name. Very cool!