Locale-plugin-ssid is a project mainly written in Java, it's free.
A Locale plugin that allows actions to be taken when a certain SSID is in range.
This is the repo of the Locale SSID plugin.
It is quite buggy and needs a lot of work, but it is functioning for the majority of its users. Since twofortyfour AM has added a warning to Locale when the user is trying to install this plugin, I've decided to put this project to rest.
Please email me with feedback of any kind.