If you are using Cadence 6.1.x, under the Options menu there is a Dynamic Display form. From here, you can turn on a popup balloon that will display the shape and layer or an instance and it's name. There are many options on the form you can play with.
If you are working in an earlier version of Cadence you'll have to write your own solution. For us, we wrote a wrapper routine for the select command. When a user selects an object using the left mouse button, information about that object is displayed in the CIW. This is simple enough to do:
hiSetBindKey("Layout" "None<Btn1Down>" "reportMouseSel()")
when(obj = css()
printf("Inst %s of cell %s\n" obj~>name obj~>cellName)
printf("Rectangle on %L\n" obj~>lpp)
printf("Object is %s on lpp %L\n" obj~>objType obj~>lpp)
This is just an example. You can add as much or as little as you want to the reporting routine.