The nice thing is you don't need a dedicated computer, you could check in from the office, where-ever you can install the software. Some people write javascripts so you can control from a website without having to have software installed. I spent three weeks away from the tanks this Christmas with a neighbor kid looking over them. I would have slept better with a system like this (plus a webcam!).
There are a lot of different commercially-available controller boards for aquariums, but this one is particularly tempting to me because it uses off-the-shelf hardware. If you're interested, you might post the link on RC and I'm sure you'll get plenty of opinions and info on the competitors.
To be completely honest, however, I wonder how much utility these are for ceph-keepers, since our systems have a lot less we need to keep in equilibrium than reefers. If we see our pH changing from our office, we don't have kalk reactors we can turn on, etc.
Dan