These are the days of cut backs. We've seen it at Yahoo and now we are hearing about it at Microsoft's adCenter team.
adCenterRep posted a thread at DigitalPoint Forums announcing the support details for the Microsoft adCenter product/service. The representative did drop a new detail that they are discounting support for US advertisers on Sundays. If you visit the phone support page, you will notice the new hours are 06:00 - 18:00 PST Monday - Saturday.
So while they are updating their logo and adding a bunch of features, if you have a problem on Sunday - you are out of luck. Some support documents for US advertisers still say seven day support, but they should be updating all the documents soon to say Monday through Saturday email and phone support.
Forum discussion at DigitalPoint Forums.