I had also heard that Sprint has to sign off on the 1.6 before they can release it...that it's not up to HTC alone. That's usually the case, or at least it was with OS upgrades on BlackBerry devices with Sprint.
I e-mailed HTC today to ask this question, and got the following response:
Thank you for your inquiry regarding Android 1.6 for the HTC Hero from Sprint.
I understand it is important that you have the latest software on your device, John.
Currently no announcement has been made regarding the Android version installed from the factory on the Hero from Sprint; however, the software will be available for downloading to the device. We respectfully refer you to our developer website
HTC - Developer Center for further information regarding this software.
I hope we have answered your question in detail, John. Feel free to contact us again if you have any further questions. In order to improve our service, I would like to invite you to participate in a survey on the worldwide HTC website at
HTC Online Survey.