Last month we started publishing the EOL dates of the supported versions of Snort from the official Snort ruleset.
You will now see that the EOL date for Snort version 18.104.22.168 is set for 2012-03-13, that's March 13, 2012.
As always, any questions about the Snort EOL policy can be directed towards me: firstname.lastname@example.org and I'll get them answered for you.
In order to subscribe now to the VRT's newest rule detection functionality, you can subscribe for as low as $29 US dollars a year for personal users, be sure and see our business pricing as well at http://www.snort.org/store. Make sure and stay up to date to catch the most emerging threats!