Was reading Steve Sofian's blog on his journey with Hummingbird to IBM Document Manager ingetration and wondering about whether Microsoft will bother to integrate with IBM DM themselves. Hummingbird are making mad efforts to integrate with Sharepoint 2003 and 2007 in the thought that if they integrate, customers won't dump Hummingbird for DM but just use Sharepoint as a Portal.
Realistically Sharepoint 2007 will do everything that is required by Hummingbird clients and if it doesn't out of the box, they'll be plenty of Vendors (or the leagues of .Net programmers out there) out there selling packages to put the functionality in there.

The Sharepoint 2007 customer base will be a lot bigger than Hummingbird and other Vendors will get on the band wagon immediately if not already with add-ins. Just try finding any developer material on Hummingbird anywhere on the web...it just doesn't exist. If you type in a Sharepoint error in Google thousands of useful blog links come up! It's going to be like comparing Windows development to OSX development.