Found a solution provided by Dave Leaver..it works perfectly.
"You can hack it to work with L.MarkerClusterGroup (so it is no worse than it is already) by changing the start of the update function in the rotate plugin to bail if there is no _icon:
update: function() {
if (!this._icon) {
return;
}
The problem is that the rotate plugin is overwriting the transform and fighting with leaflet on it.
I recommend instead using a DivIcon with a child element that has the rotation, that way leaflet can happily update the transform to move the marker independent of the rotation.
As a totally broken example:
var m = new L.Marker(getRandomLatLng(map), { icon: L.divIcon({html:'<img src="http://cdn.leafletjs.com/leaflet-0.5.1/images/marker-icon.png" style="-webkit-transform: rotate(39deg); -moz-transform:rotate(39deg);" />'})});"