Well, I believe that the plot lines revolving around the three "destroyers" blend in along with Moridin's identity. I think there are three aspects of the Dragon right now.
- There is Rand al'Thor, the Dragon Reborn.
- There is Lews Therin Telamon, Lord of the Morning, echoing from within Rand's head with his memories and personality.
- There is Moridin, an 'otherworld' aspect of what LTT could have been if he had fallen into the Shadow; he is strong, as much as the strongest of the Forsaken, really knowledgeable, and he was never really bound like the Forsaken were.
Granted, it is more likely that Moridin is Ishamael, but on the other hand it doesn't really make sense; why would he hide his identity from the rest of the Forsaken if he is the first among them? Furthermore, I don't think that Lews Therin would refer to Ishamael as "the other one", he'd probably have used some quite more specific words, given the nature of their relationship. The term implied some familiarity, some way they are bound.
Or, of course, it could be yet-another Jordan Trojan horse to be resolved three and a half books from now. Who can say?
wotmania says: I would have to agree it is more likely that Ishamael is Moridin. But I also tend to think things would be slightly more interesting if Moridin was some crazy alter-world Dragon that turned to the Shadow. And Jordan has a habit of making things interesting... 
Pento McGreno says: 3 and a half books? Well, someone's optimistic...
Moridin may well be the third destroyer, since it's possible that he somehow invaded a piece of Rand's mind when OP balefire crossed TP balefire in SL. Jury is still out on whether that was intentional. Perhaps Ishy/Mor wanted to give Rand a taste of real evil, and didn't expect to have his own bell rung for the trouble.
Moridin is, however, Ishamael. Demandred's POV in a Forsaken meeting notes that he (Moridin) always was mad, considering the regularity of the saa in Moridin's eyes. Other comments are very familiar in nature, as of someone the other Forsaken knew well, and only correspond to Ishamael's personality.
Call_me_Tim
Call me Tim
well Jordan has been saying for the last three books that it would be at least another three books and also that the last battle would probably cover an entire book and seen as in book nine there is no longer the taint on saidin I think the plot will speed up a little..... so 3 1/2 is a little optimistic (if we're wanting the series to end as soon as possible which I CERTAINLY DON'T WANT!!!!!) my 2 cents
As far as Moridin keeping his identity secret from the other Forsaken, remember how paranoid "Chosen" are. Do you really think he would reveal himself if he didn't have to?
Also, what gives you the idea that he is alter-world at all, Aielyn? He could be, but I do not think RJ would pull something like that without some precident.
is Sparticus.
= 
Mor=Ishy