oh, to further explain for jhustead's question about 'saving layers for use in PhotoShop':

Because e-frontier has now 'Fixed' it so that PSD and TIF formats no longer save out that nice Alpha Channel but instead saves out a Solid White usless channel that you can just go ahead and delete (it serves no purpose whatsoever). You now have to render however you wish, set up your image either with background or without - all depending on your structure, myself, I like rendering my characters IN their scene so they are fully interacting, shadows and all and then 'lift them off' as described with the PNG.

Seeing as how you can no longer just use the selection tool  to Select From Image, you know have to render a Separate image, rendering your 'Alpha' section over 'Black' and save as a separate PNG, now you open both your background image and your PNG at the same time. Now there are two ways from here:

1. If your characters are already rendered over the background (the normal way - but e-f says the "wrong way") then you simply make that image active in PhotoShop, go to the menue and Select -> From Image and in the dialog window use the pull down menu to select NOT your PSD or TIF but your PNG and it will select your subject (forground item or items) and you can now Copy/Paste and voila, you have them on their own Alpha Layer - as in that Lens Blur tutorial that no longer seems to show here...

2. If your background image is void of your subject then you will just open your PNG, follow the selection steps above and Copy, then open your background and Paste into it.
   Mind you, this way means that you did NOT render a 'scene' that you are postworking, for your subject will not be 100% interacting with its suroundings and there are a lot of other stuff to prepare for and take into considerations so you get a proper final image that doesn't look like you pasted a cow into an underwater scene or something.....