It will be interesting when those who hasn't been online for awhile comes back and discovers it.
Yes, it was a very unwelcome surprise for me today, and I think an unfair decision. I am one of those who probably lost information for good. I always deleted PMs that had been processed, and only kept about a dozen messages where I still had to do something or which contained other valuable info.
I think the one week ultimatum was unreasonably short. Somebody could easily be away from SP for this amount of time (in the mountains, away on holiday or busy with work). Putting up this thread did not help this same group of users. Sending an automated email to all users (probably not too difficult to make a script for this) would have helped the third group. Giving a grace period of one month would have probably greaty reduced the number of users suffering from this decision.
Why did this have to be carried out in this fashion?
Issues surrounding retaining/deleting user information should always be top priority issues in software development IMHO.
I am really disappointed by the way this was handled. Imagine if your email provider or your sysadmin at work did the same to you. I probably lost a dozen messages, but I guess many other people will be hit much harder.