In [COT: 22, One Answer, 525-526], Pevara (a Red Sitter in the Tower, and one of the Black Ajah Hunters) shows Tarna (Elaida's new Keeper) a note from Toveine (one of Logain's AS Warders) that had come via one of the Red agents in Cairhien.
(Why Cairhien? This confused a few people. Remember that in the Prologue of COT, Logain's party went first to Cairhien, then to Rand in Tear. So Toveine must have given the note to a Red agent in Cairhien while she was there.)
We're not told what's in the note, only Pevara and Tarna's reaction to it:
"This changes nothing," [Tarna] said flatly. Coldly. "It only makes what I suggest more urgent."
"On the contrary," Pevara sighed. "That changes everything. It changes the whole world."
The thing that Tarna had just suggested was that Red sisters must bond all the Asha'man as Warders, in order to "handle" them [COT: 22, One Answer, 524-525]. So, in light of that, what news could the note have held?
The three most likely possibilities are:
All of these possibilities have obvious relevance to the topic at hand, and all three could be considered of monumental, "world-changing" importance to the Tower AS. It's possible, of course, that Toveine's note mentioned all three events, but the note seemed to be very brief, so for the hell of it we will just assume it only related one piece of information.
In the prologue of KOD, the Reds are reviewing a similiar letter from Sashelle. Sashelle was one of the sisters who was stilled by Rand, Healed, and then swore fealty to the Dragon Reborn. Her letter to the Reds gives the details of her circumstance and the Reds react with considerable shock.
Javidhra growled..."Gentling cannot be Healed! Stilling cannot be Healed! Sheep will fly first! Sashelle must be delusional."
"Toveine might be mistaken," Tsutama said, in a very strong voice, "though if she is, I can't see why these flaming Asha'man would let Logain be one of them, much less command, but I hardly think Sashelle could be bloofy mistaken about herself."
So it seems the most likely that Toveine's earlier note contained the news that gentling had been Healed. It's still possible that her note spoke of Asha'man bonding sisters, and of the Cleansing, but it's only the first one that we can say with any certainity was addressed by her note.