Navigate to Adobe Photoshop CS.app » (Control-Click and choose Show Package Contents » Contents » Resources » asn. In that folder, there should be a single file called PS.SIF. Rename the file to PS.sif, and Photoshop should now launch. The same thing needs to be done to ImageReady to get it to work. Note that I've only tested this with Photoshop CS and ImageReady CS, which are the only two CS apps I have. I can't speak for whether it works on any of the others.
It seems like a bit of a shame that Adobe couldn't take the five minutes to rewrite their installer app to name the file correctly, and save the rest of us a lot of wasted time.
If you're looking for another solution for a different piece of CS (ex. 2 or 3) software, for which this doesn't work, you could try out the make a disk image to install Creative Suite approach, which should, as always, still work.

