Ok, I got the 'Apple Universal Dock' after all.
This dock allows me to play music (dock line out to amp line in) while charging the phone, and the phone sits upright so I can see who is calling (and the amp automatically mutes). It also comes with a remote, which is nice so I can control the iPhone from my desk.
My bluetooth headset completes the package - if I want to take the call, I just press a button, the music mutes, and I take the call.
And the sound is great. What a deal!