The Discordian Date is currently Pungenday, the 40th day of Discord in the YOLD 3190
I'd tell you where to get the source, but there doesn't appear to be any particular special place to get it from. Since it's Public Domain, I appear to be allowed to put a copy here. And the manpage too. Anyway, I blame Slackware Linux for getting me obsessed with it.
On the subject of Discordia, the Principia Discordia may be read here.