I am not certain about this, but I think true TrueType fonts are only slightly improved by font smoothing technologies like ClearType and Quartz. Where as fonts made specifically to be used with ClearType look like utter crap on LCDs without it.

And that is Microsoft's way to embrace and extend TrueType fonts in a proprietary way, make them look like shit without the Microsoft proprietary ClearType.

Obviously this can't be true for all fonts, but if enough people, running MS Windows on LCDs experience the difference, then perhaps Microsoft can create the perception that ClearType is essential for any font to look good.

That's what I was trying to get to above, Microsoft has clearly embraced web fonts, will it also try to extend them in a proprietary way?