Is there such a thing as a machine readable (csv, xml) list of all available updates and download locations for Microsoft products such as Windows Server 2xxx? Basically, I would like a version of link text that I can run a script over to report what's available and possibly download.
It's overkill I know, but you could potentially set up a WSUS box and read from it's database.
You'll need to be aware that the situation with Windows updates is not quite as simple as you might like. There are chains of dependencies, superseded updates and cancelled updates that you also need to keep on top of. In the end anything you make yourself would essentially be a reverse-engineering of WSUS, so you may as well just use that.