I am curious about the upcoming Yun board. It looks promising.
The main reasons I haven't used the previous Arduino Ethernet is the lack of out-of-the-box unique MAC address, limited out-of-the-box provisioning support, and lack of out-of-the-box ethernet bootloader. (and it looks like trying to fit all that in the Atmega would be tough, not to mention the already limited space for parsing web-requests, etc.)
On the Yun, Is there going to be a built-in bootloader for the Atmega over ethernet (web-based)?
What about updating the code on the Open-WRT side? Flashable via ethernet (web-based) as well?