Sorry I misread that. But I'm fairly certain that Apple's method positioned text to less than a pixel anyway, just as a side effect of their general method. It's the Microsoft school of type rendering that tries to grid fit and therefore is excited about having a finer grid of (sub-)pixels to fit to.
I can't Google up a definitive answer but this document comparing Adobe type rendering against Cleartype seems to suggest that what I say above is true.
Microsoft and Adobe: Sub-pixel Positioning and Kerning:
It's fairly obvious that Apple use the same basic system as Adobe. This renders text on a grid that is far higher resolution than the screen then resamples it down. Anything that doesn't round to a pixel is pretty much by definition sub-pixel, and the colour fringes you see when zoomed in clearly show that they're using the individual sub-pixels independantly. I'm not really sure how you could achieve this without what Microsoft call "sub-pixel positioning". It only appears to be a feature with a distinct name because they left it out in their first few versions of cleartype.
Old-skool referred to a) the fact that it's subjectively more pleasing to those who are used to aliased, bitmap fonts hence the big demand for "terminal" or programmer fonts in that style, even today and b) the fact the rising DPIs have been on the cards for a long time and are now arriving, making cleartype technology, and the aesthetic philosophy behind it, basically redundant.
I don't really believe it's more technically advanced, just a different style of rendering that worked with a different set of technological and user-defined constraints.
(For what it's worth, when I looked up what sub-pixel positioning was, it was listed next to Y-axis anti-aliasing with equal billing. Again this is just built into the Adobe and Apple approach from the start: http://msdn.microsoft.com/en-us/library/ms749295.aspx#y-dire...)
Do all of those render identically on Mac OS X, or are the colour fringes different for different i's? They render differently on Windows with DirectWrite. If they render differently then you know you support sub-pixel positioning. (I can't claim the inverse, of course.)
> b) the fact the rising DPIs have been on the cards for a long time and are now arriving, making cleartype technology, and the aesthetic philosophy behind it, basically redundant.
How is this so? As DPI goes to infinity, both ClearType and Quartz will look exactly like they would look in print.
I can't Google up a definitive answer but this document comparing Adobe type rendering against Cleartype seems to suggest that what I say above is true.
Microsoft and Adobe: Sub-pixel Positioning and Kerning:
http://antigrain.com/research/font_rasterization/#toc0003