Question: I'm wondering if there is any news about a "Android Dev Phone 3"? Is an updated hardware of the "Android Dev Phone 2" that is coming soon? (probably an unlocked version of the Nexus One)

Answer: 
There is no news or suggestion by Google, nor are there any leaks as of today.
"The Nexus One is no longer available for direct purchase from Google, but will be made available through a partner for sale to registered developers. Please check back for more updates regarding developer availability."
<http://www.google.com/support/android/bin/answer.py?hl=en&answer=166508>