Unfortunately I can't remember any other specific examples, but I've noticed the effect a few times on blog-style sites over the past few weeks, and it's sufficiently infuriating that you really wouldn't miss it.

I've been assuming it's someone's "clever" JS snippet doing the rounds, perhaps trying to normalise behaviour on some mobile browser or something along those lines. However, looking for obvious things like an onscroll or onmousewheel event handler attached to any element in the DOM turns up nothing, so whatever technique they're using to do it is new to me and I don't know how to turn it off. :-(

I'm running release channel Firefox on Windows 7 if anyone's curious. A range of other pages I have open in different tabs right now are all scrolling at my normal (much faster) speed.