What do you do with your loved ones Facebook page when they pass away? Submit a Memorialization Request. Facebook will then lock the page for updates, content can't be removed and friends can't be added or removed. In essence, the page remains static once it's memorialized. Of course Facebook will also allow the removal of the account after someone passes.
Twitter is a bit different and more formal. Twitter will remove the account once a death certificate and link to an obituary is sent to them along with the request to discontinue the account.
LinkedIn will request a form be completed and then they will get back in touch with the submitter to remove the account.
The point is - social networking has become mainstream. It's another area to be cognizant of taking care of if you are the executor of an estate.