I have a Nexus One. I had a problem whenever anything was plugged into the 3.5mm jack and I unplugged anything the 3.5mm input, whether I was receiving a call or not. After unplugging, there was no audio coming through the headset's internal speaker for calls or when I tried to play music. It didn't matter whether it was headphones or my stereo monitors at home. Unplugging the Nexus with this bug was particularly problematic as the headset would not ring for calls. I initially discovered that I could just toggle between sound off and sound on and this generally took care of the issue. But not wanting to have to take this extra step every time I unplugged, I tried a battery pull since rebooting wasn't really helping me. It had been recommended by a Motorola Droid user who had reported this as a known bug with the droid. Seems to be occurring only on Android 2.X phones. It worked. I can now plug and unplug and the Nexus switches reroutes audio from the 3.5mm jack to the handset's speakers. Anyone know why pulling the battery fixes this (at least, temporarily)?