This may sound like a silly and trivial problem but I have a screensaver (.saver file) that is PowerPC and will not work on my Intel-based Mac. Is there anything I should try before I move on? Thanks.
I'd noticed the same thing, and I'm fairly certain that you'd need to run the screensaver subsystem in Rosetta to get this to work. Which is probably possible, but there's no easy way to do it.
Screen savers (.saver bundles) are not executable which is why there is no "Run in Rosetta" option. They are loadable bundles (basically plugins) which get loaded into the screen saver engine. To get one PPC screen saver to run you'd have to run the entire screen saver engine in Rosetta including any other screen savers until you change it back.
I was thinking maybe that the screen saver engine is an easily accessible application (like, say, Finder or Disk Mounter), in which case you'd be able to Rosetta it, but on a cursory search, I didn't see it with the rest of such system bits.
I think it's a private framework or something similar that runs under a fairly low level (and important) process. If you preview a screen saver in System Preferences no new executable gets launched and all the CPU used by the saver gets assigned to System Preferences.