Granted, if you have already upgraded your WordPress installation to 2.8.4 you are protected. Chances you you haven't. I'm not scolding you, I'm commiserating. You have a business to run. Receivables, Payables, Payroll. Not to mention working your tail off to produce your company's product or service.
You have important things to do. Keeping your blog's software up-to-date to insure that the latest security holes have been plugged should not have to be one of them.
Wordpress' overly-simplistic answer is:
the WordPress community has tried its darndest to make as easy as possible with one-click upgrades.
The problem is that in my experience the one-click upgrade seldom executes flawlessly. In fact, here's a lovely little snippet from the Upgrading Wordpress page:
Isn't that just dandy?
if you run into problems Upgrading WordPress with the three Steps described here, you need to revert to your old version first before using the more detailed upgrade instructions (ie. restore the backup made in step 0). Even though you might not run into any errors with this process right away, you might run into problems later down the line. Then it may not be possible to revert far enough back to fix the problem without losing any recent changes. So
If you use Plugins and Themes other than the ones that come with the default WordPress installation, it is advisable to start over with the more detailed upgrade instructions.
So when people ask me why I I am so passionate about TypePad as the best platform for your business blog, This is why. Or at least one of the big reasons why. If you have a Typepad blog then all this stuff is taken care of for you. No worries. Just blog.