Wasn't aware of it using DB2, not that I care much what it is as long as it works. As you probably know having worked on it it's an application platform too, which is mostly what we use it for. Sadly, none of my colleagues has the time to develop any apps for it and I only dabble around in high level languages, so everyone just uses the blank office template and creates documents with tables and stuff. But the search is great, and the save conflict management keeps some of the IT-related headaches away. I wish there was a self-hosted web app equivalent though as the UI for editing is similar to Ms Office, thus easy for Average Joe to grasp. The drag-drop storage of files inside documents is nifty.
Poor Domino. Domino is a NoSQL-ish distributed document database and application platform that traces its roots back to 1989. Mail is just one possible application that happens to come out-of-the-box. Domino was mismanaged by IBM after its purchase of Lotus. If IBM had only provided more killer apps out-of-the-box like project management, etc that businesses need (instead of hoping 3rd parties would write 'em) it could dominated (pun?). Instead, we have MS SharePoint (blah!). In fact, today Domino sucks ... but I do get misty eyed thinking about what it could have been.