I now have a Mac running OS X Lion and, unfortunately, it cannot run my old copy of Photoshop CS.
Buying Photoshop CS5 is awfully expensive. Even the student and teacher edition is more than $300, while the Creative Suite is more than $500.
Aperture is only $80 from the App Store. What’s more, I would be allowed to install it on any Mac I own.
From what I have read, it definitely has better native RAW support than Photoshop CS (I don’t know about CS5).
It would mean learning some new software and probably losing some capabilities, given the degree to which Photoshop is a more comprehensive and sophisticated piece of software. Still, it might be worth trying in the interim. If it turns out to be unacceptable, I can start saving my pennies and waiting for Photoshop CS6 to be released.