They're running Wordpress Mu which sometimes "lags" behind the normal Wordpress. For long time after 2.8. came Mu was still 2.7.1, and just recently they have cached up to 2.8.4a.
Yeah. That's pathetic. You should erase any signs of the WP version you actually use as this is an open invitation for hackers.
The only thing you're preventing is people reminding you that you have an old version. Worms, spiders and exploits doesn't check your version and someone checking will just see that you have removed it and try anyway.
There are still plenty of malicious scripts around that check the version. More advanced ones can't be fooled by that of course.