Microsoft has announced several things with regards to the adCenter.
First thing is a name change from MSN adCenter to Microsoft adCenter. Know one is quite sure why they made the name change.
Next is the fact that the adCenter in the US is now open to anyone. Previous it was invite only, and they had a few open days when anyone could register. They also announced that a UK version of adCenter is coming soon.
The most interesting announcements for publisher is that they will start ContentAds, their contextual advertising, this summer. For now it looks like the contextual ads will only appear on Microsoft’s own web sites. There doesn’t appear to be any word yet on when publishers will be able to sign up to get ads on their own sites. Microsoft seems to be taking its time launching something that will compete with YPN and AdSense for a slice of the publisher market.
More analysis is available at at Search Engine Watch.