Though not a big enough deal to have, and nor would it keep me from subscribing to an MMO, but I would enjoy it.
BUT what I WOULD love to see, is the option to continue typing, and talking to people as I zone.
In every MMO, transition to Instances and such, it's not a big deal, but being able to continue my conversation, would make the 'wait' a bit less noticeable, and just in general, add a bit more conversation, in moments where no one is talking in their LSs/PTs.