One game that has recently integratied VOIP in an interesting way, is second life.
They use a system where by the chat you hear is localised, so if you're on the bridge, you wont hear chat from 2 decks down, and, in turn, as you move around the bridge, the perspective of what you hear changes.
A very good system, that works very well, all the time, with no lag at all. The bonus is, it uses a mere 4-5kb of bandwidth per second, a doddle for most net connections other than dialup - lets face it though, if you're playing an MMO on dialup...well, wake up!
VOIP is at a point where it can work very well in an MMO, and i would love for it to be in STO. At least have the option - for the people who dont want to talk, you can still listen, please!