Is there a display on the HUD that tells who is talking?
I believe the player's icon flashes.
IE: if you are standing behind a recon and a specialist, and the recon says something, the little triangle above his head animates and kind of flashes. At least I think that's what the cause of the flashing is :P
I'm anxiously awaiting a new gaming headset to start barking orders at my teammates!
In the meantime, when there's someone on my team with a mic, I often ask "the mic guy to help coordinate the rest of us nitwits". I guess I should ask differently because so far all it has done is made them keep quiet for the rest of the game. Occasionally, I'll be lucky enough to be thrown into a team with a couple mic'd people that are well coordinated -- in those cases, it's fun to "follow orders" and contribute to the win, even without a mic.
Their needs too be a indicator above your weapon hud in the bottom right of the screen. When a person talks it should display their name their along with that person's little VoIP bubble lighting on themselves. This would allow me to know who is making the call out and more easily adjust my position to theirs imo.
Most people disabled in-game voice communications because it's populated by tryhard 12 year olds getting mad at everyone on their own team because they aren't all MLG1337Pr0.
I've used TeamSpeak and Ventrillo exclusively for my gaming chat needs for 7 (+/- 1) years of gaming now. It's just so much better to communicate with people you know aren't going to be called away to do chores by their mom half way through the game.