We've been playing with Aperture to see if it's possible to integrate it into a bigger workflow. For grins, I tried it on the business boxes (mini and iMac) using the installer hack that bypasses the hardware check.
1 GHz seems to be about the bottom end of being able to use the program tolerably (for certain definitions of tolerable). Importing and organization is slow but reasonable, about on par with Bridge for most operations. The UI generally keeps chugging along even if the hardware isn't up to doing fast imports, beachballs are rare.
It turns out that Core Image hardware is not even required for everything to work, and all the filter controls are still responsive -- the UI is good enough to allow user input even if operation aren't complete -- but obviously, image updates aren't happening in anything resembling real time without a supported GPU. One could, in a pinch, still get actual work done. Not-so-interactive operations, such as the lift and stamp stuff, ought to be fine since you can wander away while they work.
The patch tool really hates living with an anemic graphics card, but a PB is much better off than the junk I'm talking about here. You will get a lot better response from the other filters as well.
Bottom line: it might be a useful tool if want raw image support and aren't going to be too demanding, just tweaking a few things here and there and not trying to process a bazillion photos an hour. It would be nice to have if the idea is simply to have the same software running on a notebook and a bigger machine back at the ranch. You may not feel like you got $500 worth of software running it on less than a G5, though.
