I speak of the actual slice areas, geometry and settings, not the content of the slices. I basically have two different versions of the same web page, that hold the same dimensions, and I want to copy over the slices from the first PSD to the second PSD.
Is it possible? Both PSDs are of identical height and width.
Not from what I know, but correct me if i am wrong. But you may want to try imageready, it has much more powerful tools for web stuff. You might be able to through that.
Yes you can, but not with just Photoshop. See this link: http://twelvestone.com/forum_thread/view/18542
You can use ImageReady to simply copy and paste all the slices. I have done it a few times myself. Works well 
You should be able to do that with ImageReady. Unfortunately I don’t have it on my current computer so I can’t really confirm this atm.
If you don't have ImageReady, there are workarounds in Photoshop. I usually have one PSD with slices defined; that file is separate from the design PSDs. There are two ways you can add the design PSDs as separate layers in the sliced PSD:
A) Flattening the designs (.jpg, .png, etc.) and pasting them into the sliced PSD.
B) "Place" the design PSDs into the sliced PSD.
Placing is a little nicer because any changes you make to the original PSD will appear in the sliced PSD as well. Basically, it is pulling "live" info from the linked file, whatever its current state is.
Info about the [I]Place[/I] command:
http://livedocs.adobe.com/en_US/Photoshop/10.0/help.html?content=WSfd1234e1c4b69f30ea53e41001031ab64-78f0.html
http://articles.sitepoint.com/article/placing-graphic-photoshop-file# (look under [B]Placing Artwork as a Smart Object[/B])
Sorry, that was kind of off on a tangent, but there really is no direct way to copy slices between PSDs.