Brandon LeBlanc from the Windows Experience Blog team has put together a list of all Microsoft team blogs that he found. I expect the list will change a little as it might not be complete yet but it is a pretty neat reference if you are ever trying to find out if "Those Microsoft guys working on XYZ product have a team blog or not".
Check it out here. Of course I made sure that your favorite Exchange blog is on the list!
- Nino Bilic