Yes, as of Issue 191. Just look at the style sheet:
The primary face is now Avenir (for those who have it).
If you don’t have Avenir but do have Lucida Grande (which comes with all Mac OS X systems), that’s what you’ll see.
Or you’ll see Lucida, which comes with some *Nix and Windows setups.
Or you’ll see Verdana. Jeepers, just about everybody has Verdana. Verdana is also the closest match to Avenir. It comes later in the list, not because Lucida is more like Avenir than Verdana, but because Lucida is a fresher choice. Verdana is so widespread (and I’m one of 50,000 people who helped make it that way) that it almost disappears, as if no face was chosen. That’s why I put Lucida before it in the list.
If you don’t have Avenir, Lucida, or Verdana, the next choices in order are Bitstream Vera Sans, Arial, Helvetica, and finally, generic sans.
No one should have a bad reading experience given that list of fonts in that order. No one.
I can imagine only one scenario to account for the problem two readers have reported.
Namely, if those readers had a bad, cheap pressing of Avenir installed on a crappy system (a system with no antialiasing), or if they had bitmaps for Avenir but no Postscript or Truetype files for Avenir, then I guess they might have a bad viewing experience. (But what web professional would have bitmaps of Avenir but no Postscript or Truetype version?)
The solution would be to use your font management software to turn off your bad copy of Avenir.
Then you’ll see the site in Lucida or Verdana or some other very common font.