At a client site, I have been testing some automated ways to move users from v1 to v2 profiles. All their users are on Windows XP and we are moving them to Windows 7. I was looking specifically for a graceful way to allow interoperability between the profile versions and keep us from having to touch every user profile to copy over data. What I found was a little annoying. There is really only two ways to migrate data from v1 to v2 profiles.
Use Folder redirection to share data between the profile versions by redirecting relevant data to a network share that can be used by both profiles.
Use the user state migration tool [more]
If you are NOT using roaming profiles, the USMT is the best way. If you are using roaming profiles, the folder redirection is the best way. The gotcha here is to make sure you create the folder redirection policy FIRST on a Windows Vista, 7, or 2008 system BEFORE editing it on a Windows XP or 2003 system. There is something about the way the GPO is created/built that will not allow it to apply to vista, 7 , and 2008 systems if it is created with XP or 2003 first.