I've not come across that one. Page zoom should enlarge everything on the page, including images (although it doesn't tend to work for other embedded objects) and layout, so certainly should include fonts sized in pixels. IE8 definitely does zoom pixel-sized text. Of course, you've still got to cater for browsers from before the days of page zoom.
With browsers having a zoom feature, I don't bother with text enlarging scripts anymore.
I've never seen the point of replicating any browser functionality with fragile and restrictive widgets in the web page - not for printing, not for going back a page, and certainly not for changing the size of the text. Show people how to use their browser properly, rather than giving them props that stop them from learning.