It says you can walk away in the middle of them speaking, and they'll eventually stop, but that could mean if they haven't finished, your quest might not update. I don't know if that's how it will be, but it sounds like it might be.
Yea but I they say something like "stay until you have what you need" which I figure would be the quest update. I figure it triggers at the start of the quest giving topics rather then the end so you can leave immediately. Staying to hear extra details might be to your benefit though.
There is still a screenshot missing.
In the Dutch magazine there is a picture of three white Ice Wraiths circling around. it's very cool, I hope Beth will release a high res version of it soon.
This one?
http://skyrimguild.com/wp-content/uploads/2011/02/skyrim_011.jpg
Source: http://skyrimguild.com/?p=212
(mods: feel free to delete if these are not allowed)
I love those things!