I attended a pre-Windows 7 launch event (on coding for Windows 7 new features) and heard it as a quick throwaway line in a longer list of deprecations, but a few did snigger at its mention. It came up again today in some reading and this time I thought perhaps to comment on it. With Windows 7, Microsoft officially end-of-lined Microsoft Agent. It seems somewhat odd to eulogize something that can still be downloaded (and considering it came bundled with XP and Vista, it may be decades before existing installs vanish altogether). But in some respects it has already been on life support for years, having never moved beyond its COM roots into the glistening managed world beyond. (Although it was one of the better COM APIs to work with from managed code, but I think the principle is clear that it was a sign of the times when it was bundled in Vista and not upgraded, and particularly not upgraded in concert with perhaps WPF.)
I wonder if perhaps Agent would be something that might have an interesting after-life as an open source tool, but I'm inclined to believe that it won't be relinquished into open source. Even if it were to see an unlikely conversion to open source, I expect that maybe even the open source community might not know exactly what to do with it...
Agent is best known for its abuses than its genuine uses. I can't think of a specific usage that ever really neared the potential for what Agent could be used for. I can only offer my own experiences with the tool, as some small, nearly useless, counterweight to its critics.
Of course, none of the above probably makes any sense to anyone without a little research on Wikipedia. I, at least, will miss a few of these animated companions when I can no longer script them to do my evil bidding, even if I (just like most everyone else that knew them) never did find that killer app to make them indispensable.