I hope they do something on the namespacing.
Linkedin appear to be including a country name in the URL now which increases namespacing, but that isn't enough.
This is one of the biggest challenges I see online and in gaming at the moment:
How do you namespace identity in a way that gives everyone an appropriate vanity URL and scales indefinitely?
Currently every system seems to end up like XBL with '{{!! MyNAMEz !!}}'.
If XBL is like this now - what will it be like in 10 years.
I think I saw some planned Google Apps profile URLs somewhere that used the format /yourdomain/name - that could be a start.