This is nowhere near ready for release, but why not show it?
Nikola can now turn this:
.. slides:: /galleries/london-paris-2012/P1000198.JPG /galleries/london-paris-2012/2P1000235.JPG /galleries/london-paris-2012/3_P1000298.JPG
Into this (which will not look good in RSS):
Support for slideshows that are not made of images
This is based on slidejs which seemed neat, but I am not 100% sure it's the way to go (it seems to look bad if the images are not all the same width, for example).