Google announced their amazing Nexus One will be available as Developer Phone to Android Market developers. Nexus one will cost about $529 and android developers will get it from with their Android developer account.
As per the note from Google Nexus One will be a good choice both for people who want to build Android applications using either the SDK or the NDK, and those who want to experiment with modified versions of the Android platform. Note that the Nexus One still ships with Android 2.1 but will download 2.2 soon after you turn it on; make sure you’re near a fast network.
Source : Google Blog