Yes, you have root, and more importantly, the engineering bootloader which will let you flash any system image on to the device.
Unfortunately, buying an ADP1 is not ideal for everyone because:
1) The ADP1 was announced after the G1 was released, so early adopters never had the choice between the two.
2) Shipping (and handling) on the ADP1 outside of the US is enormously expensive. 200 USD to Canada for instance. The author is in the Czech Republic, so an ADP1 would probably cost him at least 600 USD, probably more.
So you can see the motivation for trying to get access to the "Open Source" phone he already has.