I was messing around with positional audio with a friend the other day, and noticed an oddity with how it is configured. The wiki (correctly) states that it is enabled by default, and it is also presented in the audio wizard. However, with most applications & games, this is moot, because you still have to manually enable "Link to Game and Transmit Position" by digging through settings > plugins in advanced mode.
Practical example: Guild Wars 2 is a game that natively links with Mumble, yet does not function properly without the aforementioned option enabled; Mumble simply won't link with the game. This leads to a bit of confusion when users enable positional audio and nothing seems to happen.
Simple fix: Enable Link to Game & Transmit by default. There doesn't seem to be any drawbacks of having it on without having positional audio enabled, and there's the added bonus of providing position information to users who do want to use this feature. It was mentioned on IRC that it seems a little invasive to go poking around memory of other applications by default, though. (This could also be enabled explicitly only for the Link & Manual plugins, to start.)
Alternative fix: Omit this option, and link automatically whenever positional audio is enabled. Potentially less desirable -- I haven't fully considered use cases for wanting one of the options on but not both.
Another alternative: Move this option to the audio wizard and audio output tab, since it needs to be enabled to be effective in any case. Potentially clutters up the UI more.
I realize 1.2.4 is in RC now (and so this is a little late, heh) but the thought never occurred to me until I actually tried to use this feature. I've marked this as current-git since this doesn't appear to have changed recently, but apologies in advance if this is wrong.