After reading of Adobe's recent announcement that, at the request of a number of national governments and banking institutions, they'd covertly hobbled their imaging software to prevent its use in counterfeiting, I felt obliged to give it a spin, to see what happens. And what happens, is this:

Scanned in with a $99 scanner and Adobe ImageReady. No errors, no problems; I added in the "not legal tender" to avoid any kind of legal stickiness. So either Adobe's counterfeit-proofing is only in their Windows version, or it's a bit more clandestine than an error message and I'm about to have a squad of Secret Service men crash through my window. I'm surprised if it's the former (actually, I'd be surprised if it's either), since, while PCs enjoy a near-monopoly, creative types tend to use Macintosh.
My thoughts on what Adobe's done? Honestly, I don't care. I don't plan to go into the funny-money business (I don't even have a printer), and I've no use for scanned currency. And while the creative types who seem to be burning their boxes of Photoshop in outrage might not like it, guess what? It's ADOBE's software, and they can do what they want with it. Yes, they should have made it known that this feature was built-in when they released the software, rather than waiting for the inevitable someone to stumble on it. But their intentions are decent enough, and even if they weren't, well, like I said, it's their software. And if you absolutely have to have a scanned-in twenty for some reason, well, go get yourself an iMac or something.
UPDATE:
I've since been informed by knowledgeable fellows at work that Adobe's counter-counterfeiting measures do in fact exist in the Macintosh version of their software. So how did I get around them while scanning in a new twenty dollar bill in ImageReady and editing the image in Photoshop?
Um, I don't know. Just lucky, I guess?