SMS and email appointment notification is now part of the OpenEMR CVS. We have tested it with www.tm4b.com; Clickatell is also supported (but has not been tested). We will add a short howto to the oemr.org wiki.
OK, the variable declarations the wiki talks about are not in globals.php, as of the CVS I pulled yesterday. No big deal, just add them. However, the wiki also mentions something about a cron job that needs to run. What cron job is this talking about? Is it supposed to be somewhere in the CVS?