The date mentioned was December 27, but has not been confirmed. The post suggests that the people participating would take boats across and attempt to land on the beach. If successful, the poster suggests that there would be a fiesta held.
The event would appear to be a peaceful protest against the August 4 seizure of the Tenacatita Beach by police and armed security guards under the direction of Jose Villalobos, a Guadalajara developer, who claims he has legal title to 42 hectares of land along Tenacatita Bay and the ocean.
Numerous court cases are ongoing.
In the past few weeks, it seemed that Villalobos' company - Rodenas - was going to open the beach to the public and possibly allow restaurants to open.
The Cyberpueblo posting indicates that is not the case.
Here is a link to the La Manzanilla message board posting: Cyberpueblo posting and translation