Script Summary: Based on the handy script by P. Organisciak, this script adds a link to the left-hand navigation bar on any event site to add it to your google calendar.
Suffice to say, I couldn't get his to work. I ended up tidying the code a bit (but left his underlying algorithm unmodified) and changed the location of the Add to GCal button to the left-hand bar. It should be compatible with any other script that modifies that bar as well.
At this time, the script does not open GCal in a new tab. Apparently target="_blank" doesn't do much anymore.