For your comfort and my own, I finally made took the (easy) step of OpenID enabling my own WordPress install, basically by just installing the OpenID plugin, along with it’s only dependency XRDS-Simple.
SInce installing in this case boils down to extracting two zip archives to <wp_root>/wp-content/plugins and activating the plugins in the Settings pane, this took about 1 minute. Setting up the OpenID plugin prefs took another minute and enabling libcurl support for php5 (apt-get install php5-curl ; /etc/init.d/apache force-reload) another 30 seconds.
Not bad. As a language, I tend to prefer Java over PHP, but this is about as simple as it gets I which deserves some kudos.
Also, providing category specific feeds is equally simple: just add the cat parameter to your current feed url with the id of the requested category. To see the id of your favorite category, just examine any category URL and copy/paste the cat parameter from there. For example:
Easy as eatin’ pie!