However, using the term "farm" to describe them does do a disservice and it paints them into an unnecessary corner. They are not so much countrified as they are traditional. To the right is a Shaw's Original, which started the whole thing in 1897. The Shaw's is still made by Rohl (http://www.rohlhome.com/) and one of the things that makes a Shaw's a Shaw's is that it's made from fire clay. Fire clay is a very specific kind of high temperature ceramic. It is the same thing that blast furnaces are lined with. When it's used as a kitchen sink, it is a material that's impervious to both insult and injury. Unlike a lot of materials, you can scrub fire clay to your heart's content and you will not scratch it. It doesn't stain in the first place, so if you do end up with a can of Ajax in your hand you might want to take a look at that. Anyhow, the Shaw's is a classic and as such it works well with virtually any aesthetic, from traditional to modern.
Once you leave the Shaw's behind though, there are a nearly uncountable number of options out there and I'm seeing a lot more of these things being made from metal. Here's a more traditional metal sink by Native Trails (http://www.nativetrails.net/). This sink is actually hand made from hammered copper with a layer of nickel over top of it. Copper is a highly reactive metal and it takes a long time for it to achieve something approaching a uniform patina. It'll be gorgeous when it gets there, but it will be anything but along the way.
The beauty to the left is a 12-gauge stainless steel sink from Bates and Bates (http://www.batesandbates.com/). The lower the gauge number the thicker the metal. A $200 sink from a home center will be 20-gauge and that's a hair thicker than aluminum foil. At 12-gauge, this baby will lack the tell-tale sound that people associate with dropping something into a metal sink. No gong here. That it's pieced and welded together instead of being stamped (the flat bottom is a dead give away) along with the superior grade of the metal are why this is a $3500 kitchen sink. You can pick yourself up now. Strange as it may sound, the world is full of people who will spend that kind of jack on a sink.
Kohler (http://www.kohler.com/) came out with their stainless steel apron-front a couple of years ago and I think I've used the Kohler Verity more than any other apron-front sink in my kitchen work. While still by no means an inexpensive sink, the Verity is more like The People's version of the Bates and Bates. Still gorgeous, though the metal isn't as low a gauge. It can be found for anywhere from $800 to $1000.
Due in a large part to their traditional roots, most apron-fronts are single bowl sinks. Since running a dishwasher is a less-wasteful use of electricity and water than hand washing dishes(counter intuitive I know but true true true), having a single bowl looks better and is all most people need. However, there are double bowls out there and our friends at Blanco (http://www.blanco.de/) have a really nice one. Blanco is a German brand that exceeds the stereotype of German efficiency and innovation. Good Lord I love a right angle and that sink over there has enough to keep me happy for the rest of my life.
So I think I'd be willing to say that although the apron-front sink is not new, it is very NOW.