Well, you have to zoom a while before you see the overlays; it will take some time to see them in the total world-map, but at the speed TheBeun is slicing, it could happen some day
About the pointers: I also find those irritating (destroys the look of the latest slices
) and it shows only the last 30 slices made. To see who owns a slice, you "just" have to single click on the slice. A balloon with the info will pop up.
The easiest way I find to see the other slices is to start from the Top Earthslicers list, pick on Slicer, use the view slices link to get the map and then use the "go" link on the very right of that page. Now, start looking into other regions, by moving the googlemap: holding the left mousebutton and moving; Double click the left button to enlarge; double click the right button to scaling down the map (but don't scale down to much, you won't see smaller slices then!).
Depending on your internet-connection speed, it can take a while to see the overlay with the slices. But, to have an idea, go and look at the Netherlands. There is quite an activity in that country