I'm going!
We're taking Amtrak from Albany into Manhattan Friday night and staying over Friday & Saturday. Saturday, we'll take the LIRR from Penn to Freeport, then the shuttle to Jones Beach. Apparently we want to get off at Parking field #5.
I've never done this before so it should be quite the adventure.
Here's a link with info that should help you out.
http://www.lirr.org/lirr/getaways/Be...JonesBeach.htm
Here's another link with the bus schedule. We want bus N88
http://www.mta.info/libus/jones_beach/n88_2008.pdf