Cyber: About Viacom...
I assume you know about 'parent companies' (Don't fret, I'm not mocking you, it's just essential to know what one is to understand the relationship)
Viacom is the parent company for Nick, TNN, and yes, MTV. MTV does indeed own Nickelodeon, but both answer to Viacom.
It's sort of like this (every level up establishes ownership)
VIACOM
/ \
TNN MTV
\
Nickelodeon
Nickelodeon bought the rights for Ren and Stimpy from Spumco (I won't explain this, I assume you already know) and ran it into the ground. Well, fast forward a few years. Nickelodeon relinquished the rights to the characters to Viacom, their parent company, meaning Nickelodeon still has the right to air the old R&S episodes if they choose to, because the old episodes are indeed owned by Nickelodeon, however, since Viacom handed the rights to the characters back to TNN, only TNN (or whoever they sublet the rights to, say an animation company) may make new episodes of Ren and Stimpy.
TNN is planning a new block of adult-oriented animation programming in Summer 2003, and Ren and Stimpy happened to be one of the projects TNN was into. (This following part is my own speculation) TNN knew that without the original creators of Ren & Stimpy, which is Spumco, that the old fans who might be interested would shit all over it, and John K. himself has expressed interest in reviving the series. (personal speculation over) So TNN 'sublet' the rights back to Spumco (meaning Spumco now once again owns the characters it created, but still must ask for TNN's approval to merchandise the characters) and now, Spumco is working on 6 new eps. of R&S for Summer 2003.
If memory serves, they plan on showing all 52 (I believe) original episodes of R&S (which is technically legal, since Viacom owns Nickelodeon and doesn;t have to pay a DIME) and the next night they will show the first of 6 new eps. of Ren and Stimpy.
Sorry that was so long. Hope that helps.
PS The mildly bad words will be a little more wilder. Think "Adult Swim"