I just got word that the Outlook 2010 MAPI Reference has been updated. Among the bigger changes, we’ve completed the overhaul of the Nickname cache article to document where to find the cache in Outlook 2010 and we’ve consolidated all of the MAPI Constants into a single article. Read about more of the changes in the What’s New article.
We didn’t get it in to this update, but I want to remind everyone that we just published a new MAPI Stub Library over on Codeplex. Documentation for this library will probably find it’s way into the MSDN at some point, but until then, you can read the documentation I wrote as well as the FAQ.