In Telepathy, I've got my GMail account set up to have a specific Nickname. However, no matter what I do, it always seems to use a different Nickname when I'm chatting.

How do I change this, if not through the account interface?

I believe that if you IM someone, it will always use the "nickname" you first used, unless they then change it afterwards. So I believe the person you IM needs to change it by clicking on your contact details.

It seems like a bug in gmail. It certainly isn't the way I expected it to work either.

I just fixed it. Turns out GMail had put my AIM screen name into my conntacts, so Telepathy had used it. Simply by deleting the contact, I fixed the problem.

Also, it was local (in my sending window it had the wrong nickname). Not remote.