I ordered an awesome wireless microphone setup directly from Sennheiser (to use for Head-Fi TV), and a Sennheiser HD 25-1 II adidas (the one I used in Head-Fi TV Episode 004 was borrowed from a local friend). The microphone gear arrived as expected. But when I opened up the box with the HD25 adidas, it seems they decided to surprise me with this custom-colored version! It looks nice in these photos, but even better in person. (The white is more of a pearl white than a *white* white.) I absolutely love it!
Thanks to Sennheiser's Eric Palonen for all the guidance on which microphone pieces to order, and for fulfilling my HD25 order with this very custom piece! Eric nicknamed this color scheme Sennheiser HD 25-1 II Original Detroit.
I've already been asked by some folks on Facebook if they can order one just like this one, and the answer is yes. However, it has to be done through Colorware. I'll try to find out more details, and post them here.
UPDATE: Contact Colorware for availability, as I am not 100% sure this model is available from them, and/or able to be custom-colored by them. Of course, Colorware can tell you for sure.