Until I had a chance to look at some new screen shots on LiveSide.Net of Windows Live MovieMaker — yet another of the Windows Live Wave 3 services going to beta real soon now — I hadn’t really put two and two together.

The lightbulb that just went off: As part of Microsoft’s mission to insure that Windows 7 and Windows Live Wave 3 are joined at the hip, Microsoft is exorcising features that used to be part of Windows from the operating system.

I had a similar, half-formed idea about this earlier this year, when I wrote “Windows 7 might go to pieces.” But now it’s crystalizing further….

Think this through: Microsoft has been hit with lawsuits (and threatened with additional new lawsuits) over its propensity to add formerly unbundled features to Windows. When I heard about its plans to tightly integrate Windows Live and Windows 7, I immediately thought that the company was opening itself up, yet again, to more potential antitrust actions.

But what Microsoft seems to be doing, instead, is continuing to gradually remove certain features — like MovieMaker (which one codename tipster reminded me last week has been going internally by the name “Sundance”), Mail, Photo Gallery, Messenger, etc. — from Windows and making them optional add-on services. (MovieMaker, for example, was cut from Windows Vista around the time of the Longhorn reset.)

Yes, these Wave 3 Windows Live services still have a software component (as required as part of Microsoft’s Software + Service strategy). But to get that component, you are going to have to download the software onto your Windows machine — or at least agree to install it if it’s already preloaded somewhere on a new system.

Could Microsoft have found a way to secure one of the flanks that its opponents have used to keep the company in check in recent years, specifically, the threat of antitrust suits if and when the Redmondians decide to bundle any new bits with the Windows OS? Can you envision other formerly bundled pieces of Windows that Microsoft could and should turn into Live Services?