Its not annodizing, its a ceramic coating on the braking
surface.
There is some debate over the usefullness of ceramic
rims (by none other than Jobst Brandt), and brake
performance in wet conditions.
For myself, I'm not sure I can really tell the difference
between ceramic and nonceramic rims.
That said, the older Mavic SSC rims are outstanding,
well built (can you say bulletproof?), long lasting.
Problem was that up until today they were only available
for tubulars. I've just heard about a bunch of custom SSC
Clincher rims (MA2s I think) built for a dutch
cycling team that have become available.
I think 2 or 3 pairs are available.

Marty