I shut the Minecraft server down some time ago due to necessary bits and pieces of housekeeping we had to conduct. Since then, Minecraft 1.4 has come out and the CraftBukkit builds may not yet be stable enough to use. We probably won't restart the Minecraft server until that time, and there's no point starting it now since most people tend to click "update now" and will likely be running a newer, incompatible client. As I've mentioned before, we're reluctant to run the latest vanilla release because it limits us to whitelists alone and greatly nerfs our monitoring capabilities.
When a stable CraftBukkit release is out, I may post a poll to see if there's still continued interest in running it. I know I haven't personally been playing it but on rare occasion, and I can tell from the logs that seems to be true in general.