Squarespace to Wordpress Importer
Please see http://www.keleko.com/2012/squarespace-to-wordpress-plugin/ for basic instructions.
This plugin will import squarespace blog posts and also download the images for you automatically. This is an early version so please try on a backup version of your site database first.
I created this plugin to help out a friend, I don't actually use squarespace, so if you would like improvements please send me your squarespace url and backup files.
There is a known bug if your image names have spaces.
This plugin is based on an existing wordpress importer.