May also be what your computers have cached already. If the site is down, and your computer has a copy of the page previously, it may show you this instead of an error message.
Whilst this might be them updating the site, I'm a little concerned with the influx of spam comments (esp from "old" accounts) that perhaps someone has taken advantage of the security flaws in the older IPB software, which has been warned about for some years.
A simple database connection problem should have been fixed by now, but, only if it's been spotted. Presumably it hasn't (and with no contact details for "mjdev", we can't contact them).