so...
can supey just use this matrix thing any time?
The Matrix came down with the fortress near the end of Reign of the Supermen. The Eradicator used up all its juice to power himself up and everything crumbled. Oh, and then the whole Byrne/Jurgens continuity also crumbled in recent issues.
and was the eradicator/ matrix thing part of the story originally, or was that just something added or clarified recently (i remember seeing that, i believe, in some of the crisis storylines, but never remember even hearing about it 5-15 years ago).
It was all part of the story from the beginning: the chain of events leading up to the resurrection was carefully set up since Funeral for a Friend. The Eradicator goes back several years before this storyline, too, though it was originally a Kryptonian artifact that later acheived sentience. The seeds for the Cyborg and the creation of Superboy were also planted years earlier (not with Superman's death in mind, obviously).
Jonathan Kent, near death, fought through heaven and hell to bring Clark's soul back. What a guy.
and wuzzis all about
That's Adventures of Superman #500, the double-sized issue between the relative tranquility of Funeral for a Friend and the craziness of Reign of the Supermen:
At the end of Funeral for a Friend, Pa Kent has a heart attack. In this issue he's in a coma and has a near death experience in which he basically helps Superman's soul come back from a fake Kryptonian funeral procession that's taking him to Hell. When he wakes up, the first thing Pa says is "He's back". Then Superman's body disappears, and the four Supermen happen to make their first appareances.
Later it's revealed that the body disappeared because the Eradicator took it to the Fortress, so he didn't simply get up and walk out of his grave after Pa's experience. The whole thing was most likely just a dream, or at least that's the way I've always seen it.
