Google has announced a unlocked and truly open android handset fro developer under the moniker "Android Dev Phone 1". As I read more, it seem to be wide open for developers. (You have to be a registered developer to be able to obtain one. follow the details later in the post.) You will be able to flash the device with your own customized Android OS, The bootloader does not check for signatures before an image is allowed to flash. This should also accommodate developers living outside the T-Mobile network. (Now I can stop saying Google Phone Coming Soon!)
Here is the information from Google;
"To purchase an Android Dev Phone 1 device, you must first register as an Android developer on the Android Market site, if you haven't done so already. Once you've logged into your developer account on Android Market, you can purchase the device by clicking the "Purchase" link. To accommodate demand, there is a limit of 1 device per developer account, for now.
The device currently costs $399 (USD) (including free shipping in the US), and will be available for purchase in 18 international markets, including the US, UK, Germany, Japan, India, Canada, France, Taiwan, Spain, Australia, Singapore, Switzerland, Netherlands, Austria, Sweden, Finland, Poland, and Hungary. We will continue to expand this program into new geographies over time. Check this page for updated information.
Note that Android Dev Phone 1 devices are not intended for non-developer end users. Since the devices can be configured with system software not provided by or supported by Google or any other company, end users operate these devices at their own risk.
For more information about obtaining an Android Dev Phone 1 device, see the Android Market site."
Initial source;Android Developers Blog: New Resources for Developers