Vertex,
Please keep in mind that Warforged are NOT machines. They are not mechanical in any way. They are constructs of living biological material (mostly woody fibers and such) and have a metal chassis, but are still animated living creatures, not just simple mechanical constructs. They do not have gears inside of them (at least not that I have ever read) or other mechanical or electrical components. Just remember that Warforged does NOT = Robot. Warforged are magically (arcanically?) animated, not mechanically animated.
To SG: I am okay with them being fluffed as psi-forged OR as their own race (which would just be easier). Perhaps they are a new creation of the Cannith? I could see them doing this in an attempt to keep doing what they were doing without breaking the Treaty of Thronehold, since they aren't creating "warforged" from their original forges. Perhaps they are constructed in some other fashion and are brought in from another realm (since if I'm not mistaken, the shardmind is also considered to be immortal, right? I don't have my PH3 with me today, but I thought I remembered seeing that... please correct me if I'm wrong)?