Sorry to chime in out of nowhere, but I've been following the recent rash of uptime complaints and I wanted to offer a "probably" in answer to your question.
I've looked around to see what kind of guarantees (or at least marketspeak) other webhosts have; There are plenty of hosts that seem to think 99.7%, 99.5%, or even 99% uptime are worth bragging about. I have found hosts offering a "guarantee" of 99.9% or even 99.99% uptime, but those hosts tend to cost anywhere between 2 and 20 (yes, 20) times as much as Dreamhost.
Personally, if 99.7% is accurate, I would call that pretty darned reliable--6 minutes a day isn't bad. You can certainly hope for more, and the functional downtime (from your area of the Internet, at least) may be worse, but I'd say it's pretty good for all but the most critical websites. If you need more, then you'll have to be willing to pay more (a lot more, mostly likely).
Incidentally, I'm seeing 99.9% monthly and all time uptime for my server, balrog, and I haven't personally caught it down (or heard complaints from my forum users) in months.
Also worth noting that mosts hosts' definition of uptime tends to be "server responds to pings from our local network", which may be very different from a normal users' "I can see my site". I like the fact that Dreamhost gives uptimes for each service--gives you an idea of when something's just not working right, and when the server is actually down.
One thing: if the people having these problems are able to access their control panel, doesn't that point to either a machine outage or some specific DNS-type glitch? Since both servers should be on the same network node, I'd imagine that a network outage would knock both out from the perspective of a user.