Using the delete with a callback mechanism should be used the moment we are dealing with items in the content repository, as you could easily clean up in TCL all the things that you generated in TCL in the first place :).
I have to say though that noone bothered so far to write delete scripts for contacts (that never came up), so I am not sure.
If you have some time, we can meet on IRC and I can give you a quick rundown what to write (roughly) in the "delete" callback for contacts and then you could write and test it yourself iuri. If you feel comfortable with OpenACS development, that is. And it would make sense during the bug stomp next week.
