I love my Touch Dual, but I'm one of those people that constantly forgets to shut it up when I'm at my desk. (This is a plea for help, rather than an apology to my coworkers, who deserve everything they get.)
But anyway: my utopian vision is that of having a USB Bluetooth dongle in my work monitor, that I can allow to set my phone to vibration- or silent-only mode.
When I wander away, it'd switch back to "normal".
I couldn't find such a thing from a web search (a mention of a Norwegian company back in 2001 that built something to turn them off in airports).
I imagine it'd have to be key-based to prevent abuse, but it sounds do-able... am I just not finding it because it's a bad idea?