facebook dead members

What happens to accounts on xanga, facebook, youtube, etc. when the user dies?
How do the webmasters know when the user of an account is dead? Do they then delete the account? Can family members and friends request to keep the account as an online memorial? What then happens to the username? Is it just deleted, never to be used ever again, or can it be ‘recycled’ and re-used by some other random person on the internet who happens to choose the same username?
our friend passed away in iraq (over 1.5 years ago) and his myspace is still active, the family logs in occasionally and it has become a memorial for friends and family. it depends on the site, but most will allow it to remain active as long as someone logs in and notifies the webmaster…
thanks!
Billy Corgan – Morning Dew (Grateful Dead cover) – 8.29.09