Adobe announced the mars project on labs . What is Mars? An XML implementation of the PDF syntax, including extensions for industry standards such as SVG, PNG, JPG, Xpath, etc into a zip file. There is a plug-in for acrobat that will support creation of Mars document in Acrobat 8. To view mars document, there is also a plug-in for Reader 8. (p.s., reader 8 is available for download now on Adobe's website.)
What does this mean?
One simple scenario I can think of, is to easily support xml data merging and extracting using commonly available tools then distribute as PDF after it has been converted from a Mars format. I suspect that somewhere down the road, Reader and Acrobat will support the Mars format natively, without requiring a plug-in.
More to come after i experiment more with the Mar's pre-release build.
David in Vancouver