more a case of I was asked if I could "finish off" some photographs I took for them, I played with CS2 a couple of years ago, but didn't get very far, didn't really have any reason to, Now I have CS4 and have spent a few days learning the basics from tutorials.
Once you know a dozen tools or so you can sort of mix and match a bit, long way to go yet, but with time and patients it's possible to achieve something looking very pleasing from what was just a good photograph (it can't be that bad as someone actually paid me for it......

), learning how to create basic shapes and put pictures on them is a good place to start I found, then manipulating them next, then lighting effects and shadow, I've no idea if that's how it should be done, but it's kind of worked so far for me.
Spheres are good and a nice effect can be had just by doing the same thing several times in different scales, also cubes and mirror boxes all just basic shapes, I also like to scratch build my backgrounds as well and save the good ones, a few borders also add to the whole effect, here's a few examples I've done over the last couple of days, I like to try and do something different and learn something each time, so each one adds to the knowledge I already have..
Cheers Mark.