Well, that, and I knew I had Ubuntu updates on both boxes. Also, being an Apple household with a lousy sense of timing, I had bought the generation of color laser printer just before the generation that had built-in AirPrint capabilities. To provide that, I bought a $99 box from Lantronix that provided AirPrint capabilities for a number of printers that didn't have it, like my HP CP1518ni.
The problem was I had a fantastic deal on a Canon B&W Laser FAX, Copier, Printer, and color Scanner, the imageCLASS MF4770n. No built-in AirPlay, but that's okay, right? I have this magical box that has over 8,000 different printer drivers. Well, except this Canon imageCLASS multifunctional unit, and the whole Canon imageCLASS line. The Canon is downstairs with the Mac Mini. Anyway, my wife wants to know why we can't print to the FAX unit from her iPad. So I tried a bunch of stuff and stumbled across CUPS.
Basically, by Folding on Ubuntu, I've had the solution to my AirPrint dilemma all long (like Dorothy in Oz). Log on to Ubuntu node. Go to CUPS home page //localhost:631. Click on Administer, then on the "Share Printers" button. Ta-Dah! Or so I thought.
Of course, the drivers aren't part of the Ubuntu distro, but I was able to download the Linux drivers for my MFP. Installing the Canon MF4770n on my Folding box now makes it available to AirPrint. Turns out, Lantronix was using a version of CUPS all along. And, more to the point, they have stopped selling the box, with support ending next year. So, configuring and using CUPS on my Folding box makes even more sense.
The printing load should be minimal, so there should be zero impact to my Folding efforts.