The NG has it as a option and some companies use it .Pegasus was one of them,on the 738 (last I know of).It appears on the EADI instead of RA indication(upper right side) ,which is displayed then on the lower part of the EADI .
It's a nice tool,but you have to learn to use it,and most of the experienced pilots will find it difficult to accomodate with.
The same with the NG FPV. When we asked about it's use,we were told to forget about it,just a new gadget.Anyway,without a cage...
good in wxr radar use,though.