Hi,
I enhanced the first extension, which was able to save a zip archive with svg and images, with an extra extension which is able to read the archive instantly. I changed the zip-extention to .zink which is of course a combination of Zip and Inkscape.
The output extension creates a zip and makes all image hrefs relative. The input extension does the reverse: it unpackes the zip and before printing the doc to stout it replaces all image hrefs with the exact path of the temp dir.
The svg in the archive is named content.svg so its easy to open. Of course a file with metadata can be packed be also, but I wanted quick results and I don't really know what to store in such a manifest because everything is said in the svg.
It works rather smooth. You won't notice that this is not the native file format. You can open a .zink make changes and click CTRL-S so it save the .zink-file again.
Please download and test it on different platforms. http://facility.lingewoud.nl/hacks/inkscape_save_and_open_as_zink/
You can also download the example .zink which you must be able to open after installing the extensions.
Hope you like it.
Pim