Lighthouse is a set of programs that allows users to access programs over IM and allows programs to send IMs to users. Some possible uses are: sending offline messages, hierarchical IMing (send a message to user1, but if they're offline, it goes to user2), alerts on receipt of email, alters on calendar events, etc.
Currently, Lighthouse uses Jaim 0.4 (included in the .tar file).
Two helper programs are included in the distribution. They are: parrot.pl (which repeats a user's IM back to them) and notes.pl (which allows users to leave notes for other users). These files aren't necessary for the operation of the Beacon, but do give some sample uses and code for those interested in using it.
To compile and run the Beacon, you'll need Java 1.4.0 or higher. To use the two sample programs, you'll need Perl 5.6 or higher. Lighthouse has been tested on Windows, Solaris, Linux, and Mac OS X, so as long as you can run Java and Perl, you should be okay.
Lighthouse documents and source code may be found on Sourceforge, along with message boards and bug tracking.