how hard would it be to write a plugin to do this?
I don’t think that is currently possible.
Someone might be able to provide some kind of hack for it, though.
write a plugin that adds a filter to publish
the plugin will have to get a code from the (mailed) post, write it away as custom values and delete the code.
the code you can put in a post could look something like this:
[customfields mood=happy lat=1.5 lon=5.2]
the plugin will add the field ‘mood’ with the value ‘happy’, the field ‘lat’ with the value ‘1.5’, the field ‘lon’ with the value ‘5.2’.
Start with the plugin called ‘YouTube brackets’, it does something similar.
http://www.robertbuzink.nl/journal/2006/11/23/youtube-brackets-wordpress-plugin/
you’ll just have to add an ‘explode by =’ for every ‘exploded by space’-parameter in the first function, and the adding of the meta-value in the second function:
add_post_meta( $id, $name, $value );
where $id is the post id.
Also, you’ll have to delete the output stuff and make some foreach structure in the first function to accommodate any number of metafields.
