I discovered this issue recently, and if you come across it, the fix is simple.
Problem: Plug in standard headset and the “headset” icon does not come on. Further, when listening to music, it doesn’t come thru the headset.
Issue: The firmware that detects the headset plugged is wonky (it’s a technical term).
The Fix: Take out the battery to reset the firmware.
There is a problem with the MESSAGE application on the Sprint HTC Hero Phone. The application fails to release it’s connection from the network and keeps the CPU running, which drains the battery faster. While it appears as an HTC Hero Battery issue, the real problem is an application that refuses to sleep.
The FIX
1. From the Android Market, download “Handcent”, which is a free SMS application. I recommend since I use it, it’s skinnable, and does “speech to text” for your SMS… which is pretty handy!!
2. Disable the Message applications notifications.
If you have any questions or comments, please feel free to ask!