After browsing teh interwebs about securing WordPress installations I found a good tutorial over here:

http://www.guvnr.com/web/blogging/10-tips-to-make-wordpress-hack-proof/

I would encourage everyone to have a look.  Beyond the usual “install the latest version” and “use stronger passwords” , there’s some other great hints, like changing the default “admin” user’s name to something else; changing the “wp_” prefix on your datatables, and using the power of .htaccess to block unauthorized usage of your wp-admin folder (and plugins folder for that matter).

For the lazy or less-inclined (your truly included), you can also try this plugin:

http://semperfiwebdesign.com/custom-applications/wp-security-scan/

Which is super awesome, and automates most, but not all of those changes.

A relatively recent review of other blog security plugins can be found over here — fair warning: haven’t tried any of them, but some of them do sound nifty.