They probably don't even look over the D2 servers during the week-ends anymore. If it was maintenance or a ladder reset it wouldn't be happening now, they'd do it on work days. The routing/networking has probably gone to hell and no one is there to fix it, that's all. This isn't WoW, and it would make perfect sense that nobody will work on fixing it until monday since they don't generate any profits from D2.
Bah I was in channels on a character for 5 minutes then got booted. Surely the servers can't handle all the mass game crashing caused by this flood of rampant duping. Add in the fact that Blizzard couldn't spend the half-hour it would take to fix the game completely and we've got a realm down that may last all weekend!