Since this topic has the most posts in it ill assume its the one of the four we want to use.
What worries me slightly about this is that Bing/Live has been pretty strick when it comes to landing pages and bidding on brand names. I have several campaigns that have been running on yahoo for years now. The same campaigns could never get off the ground on Google or Bing/Live due to trademark protection and 'unrelated' site content.
So either I will be able to continue to run these ads with an increased search volume or I am going to be screwed by Microhoo's new guidelines.