Alex over at The End of Cyberspace writes about the functions of remembering and forgetting past acquaintances when it comes to social-archival services like Facebook. He makes a good point that these entities seem driven to eradicate forgetting in one way or another and notes that forgetting does have an important cultural role in subject formation:

"...when it comes to shaping identity, the ability to forget can be as important as the ability to remember."

Yet I don't think - given the current state of things - we're in danger of unrelenting remembrance thanks to the pattern of people moving from one service to another as they tire of its offerings. Maybe one day our networked, subjective data will follow us around no matter where we go, but until that day forgetting will happen as long as attention spans are short.