Cost of hosting, minimal
Having a host to worry about this sort of thing, priceless.
Doc Searls Weblog · Attention WordPressers
“Take it from somebody who lost at least one whole blog entirely from the consequences not upgrading WordPress: Upgrading your installation or patch is essential”
“What’s happening is: spammers are taking over blogs, posting link farm links on them, obscuring their human visibility with CSS tricks but the links are still visible to crawlers…
All wordpress users that haven’t patched or upgraded to v2.3.3 are vulnerable.”