The problem is that kiosks with 24/7/365 uptime demand... well, 24/7/365 uptime, which ideally means some way to detect memory leaks and watchdog the thing.
If you're cutting the power every night, you can use anything ROM-based, really. Or anything that can keep its filesystem writes synchronous/atomic.
Everyone loves the fast boot time and the low resource footprint... but how often does anyone boot anymore, rather than taking a machine out of suspend? (Admittedly, Vista will probably take five minutes to come out of hibernation even though it's now the default...)
I think this means the real niche is down in the fabled embedded space, namely ubiquitous, practically disposable devices -- pull out something the size of a pack of cards with your presentation preloaded, plug it in, and...
I've just described the iPod. F***.
