I've written a small Wordpress Plugin that implements a glossary similar to Radio Userland or PyDS. The glossary simply replaces text that is delimited by | (pipe) symbols with replacement text (which can also contain XHTML markup). Saves typing ...
The plugin installs a small management page in the Wordpress backend, so the whole thing only works with Wordpress 1.5 (or possibly 1.3). The required database table is automatically created upon plugin activation when you first access the management page.