Some time ago, I moved my blog from NanoBlogger to ikiwiki. To this end, I wrote a small perl script for handling the conversion. It only requires the modules Date-Manip and HTML-WikiConverter-Markdown. After installing them, you are good to go.

To use the script, copy all your NanoBlogger blog posts (along with their category data) into a folder. Usually, it is sufficient to copy the data folder of your installation. Keep in mind that the *.db files are useful if you want to keep your tag information. With all that set up, set the variable $input_directory to the directory with your NanoBlogger posts and run perl nb2ikiwiki.pl.

The script will automatically parse your blog posts, convert them to the Markdown syntax, apply any tag information (if specified), and store them in folders by years. Each file will be named after a sanitized version of the title of the article it contains.

This conversion process was sufficient for me. Hence, there are no further configuration parameters. You are free to modify the script in any way so that it suits your needs better.