This is partly a shameless plug but you can check out the incomplete (still in development) project called Mad Bee (Managed Android Debug Bridge). It is a port, plus some modifications and extensions to the library used by DDMS to communicate with an ADB server. this will not replace the ADB server, but it communicates with it over TCP just like the adb client does. Feel free to contribute to the project too :)
It can get attached devices, list files, execute commands on the device, plus a ton more. The incomplete part at the moment is the "device monitor" that monitors if the device state has changed and initializing the actual android debug bridge.