If you’re having trouble getting Google Maps marker clustering working on IE8, this little snippet may be of use.
var markers = [[123.234,213.345],[672,123,125,554],];
The problem with that array is the trailing comma, something that’s often present when you create an array via a programming loop. Remove it so the array is as follows and you should be good to go. Modern browsers are able to ignore this problem, while some.. not so much!
var markers = [[123.234,213.345],[672,123,125,554]];