In May, Barry reported that MSN adCenter would be offering an accreditation program. At this time, it's only available in beta to customers residing in the US, according to adCenterEU. By the end of this year, it will also be rolled out to UK customers.
The program is called adExcellence. US users interested in opting-in can sign up on the pilot program sign-up page.
Forum discussion at DigitalPoint Forums.

Comments:
adCenterEU
10/08/2007 02:06 pm
Hi All Thanks for this Tamara! Just to clarify - we are piloting the adExcellence Program in the US right now and hope to start a pilot in the UK by the end of the year. Cheers adCenterEU
Tamar Weinberg
10/08/2007 02:26 pm
Thanks for the clarification, adCenterEU :)