The Google Calendar Widget is EXACTLY what I need - and it looks great too!
I tested this on a Linux installation and it worked great; so full of confidence I installed it on a WordPress installation that is being set up for an astronomy group I am involved with.
Despite identical settings I just could not get it to work (I'm using IE9). The loading animation just shows continually. I tried it again using Chrome - and it works just fine! With IE9 in compatibility mode - still no joy.
I'm not aware of any IE9 settings that would be blocking content... any suggestions?