I didn't get that far, but I assumed that it surely would. Still, there will be many people who will be unaware of this, at least long enough to make an initial snafu.

There is an obvious "hide while typing" check box (At least in the current version).

How did you get hold of it?

I saw the demo at google IO. Attendees have early access to develop.

And then the person at the other end thinks "wtf is this guy hiding? Is he even talking to me?". Technical limitations can be very useful to avoid awkwardness sometimes (like the fact that if I don't answer an email within 30 mins it's not taken as a snub - unlike a text message people don't presume you have constant access).

I'd rather change the social norms than continue working with limiting technology - wouldn't you?