CS2 should open the file, but some of the layer content will be missing because the document uses features that are not in CS2.
Thank you for the reply. I was afraid of that, although i knew VSOs are a recent development. Is there a way to include an editable vector Type layer in the unflattened file that will be readable in CS2? Or do I need to Place the PS layers and save everything in Illustrator instead?
A plain type layer should work just fine, but will lose some of the paragraph formatting.