Alright, since I've got Dungeon 144 in my hands now:
Sharlocke - advanced arcanaloth (sorcerer 2 / archmage 4). He acts as an agent in the adventure Diplomacy on behalf of the yugoloth heirarchy, or at least his own interests and those of his immediate superior in Sigil, the Marauder, who herself acts in this particular case on behalf of an unnamed figure much higher in the 'loth heirarchy (Helekanalaith in Gehenna, or Mydianchlarus in the Waste are suggested).
Helekanalaith the Keeper of the Tower Arcane - finally mentioned in 3.x. His name is dropped as a member of the yugoloth heirarchy.
There's also the first 3.x mention (in passing) of the Tower of Incarnate Pain.
A bit of 'loth internal politics is also mentioned, in that there's something of a scramble going on behind the scenes by a number of powerful 'loths hoping to find the Staff of the Lower Planes. Originally the possession of Anthraxus, he appears to no longer have it, apparently not since he was deposed by Mydianchlarus and went into self-imposed wandering, and its current status is unknown. Various 'loths want it, both for its immediate power, and presumably for the symbolic power that it represents if they ever wanted to make a push for higher status, Oinoloth or otherwise.
Also, the revised 3.5 arcanaloth (though not presented by itself, but as part of Sharlocke's stat block) is nice. 'loth DR, in his case at least, is now 15/silver and good.