The fellow is an Australian named Tommy Emmanuel, and Greg said he played a piece on the show that was so remarkable other guitarists should stop playing the number. (Even Garrison Keillor said after the performance that it was probably discouraging for young players to hear that. Though Emmanuel said it was meant to be encouraging. After all he'd started playing the guitar when he was just seven after hearing the great Chet Atkins play.) The show was available online in a PHC archive, and I listened to it, and...well, yes, it was remarkable.
Greg said that he's subsequently seen Tommy Emmanuel in concert three times when he's come to the Bay Area, in Northern California. And he sent me a video of another performance -- one which is otherworldly. It's from a concert in Seoul, South Korea. Stick with it through the long percussion-style opening, which is seriously impressive on its own.
It's rare that you think of a guitarist as a showman, but that's what Tommy Emmanuel is. And a spectacular musician, as well.