I've worked with it before, 2 years ago when I was working with a defense contractor. There, they used it as a way to not have to write C++, and since they were electrical engineers and not computer guys, I can get not wanting to write C++. That's the closest I've ever gotten to being paid for it myself. But I had enough problems figuring out some problems with the generated code that I soured on the concept of Graphical Programming.
Until LifeHacker came up with solutions for improving your Google Reader feeds, including Yahoo Pipes, which has it's own Graphical Programming bit.
I've done a few. I've taken the Craigslist instrument feeds and searched out organ and Fender (as Fender guitars and amps and Hammond organs are the things I most want), and pulled out Pimp My PC from Butterscotch, as well as FLOSS Weekly from TWIT.TV.
It's a neat thing. I haven't done much more than touch the most simple part of it, so we'll see how it goes, if I can make it do stranger things. But it's a neat idea.