This question is locked. New answers and comments are not allowed.
This works with telerik version 2011.2.920.1040.
It doesn't work in version 2011.3.116.1040.
The same issue can be seen here
http://demos.telerik.com/Silverlight/beta/#Treemap/FirstLook
1) hover over any tile. tooltip display
2) switch over to Code tab
3) switch back to Example tab
4) now hover over any tile, tooltip not showing this time.