The classic Shockadin has a build that is deep holy (typically 40) and then 21 in Ret to get nice things like improved judgment, improved SotC and Sanctity Aura. The approach is to cast and judge SotC, then cast SoR and alternate between Holy Shock and judging SoR. It becomes much more viable in Outland, as the above quotes state, because in Outland you get access to a LOT of +spelldamage and +int plate. It's a fairly mana intensive playstyle, of course, but if you use BoW and have a good amount of +mp5 gear (which again you should get quite a bit of in Outland), you can go for a bit without having to drink. Basically the Shockadin is a nice setup for people who are going to be mostly healing in groups, but who want some solo-ability for the rest of the leveling in the 60-70 range, or for farming thereafter.
A variant on the classic Shockadin puts points in prot rather than ret, sacrificing a bit of damage potential for a tougher defensive posture. Some people prefer this for PvP because of its increased toughness and the availabilty of improved concentration aura.
It's definitely a very viable spec with Outland gear and its +spelldmg. People might be surprised at the DPS output of a well-geared Shockadin, to be honest.