I installed the Sept CTP kit for InfoCard and the February CTP for WinFX on WinXP SP2.
If I try to open the Digitial Identities applet as a non-admin user, nothing happens. No events are logged.
If I switch to an user with admin privledges, it works just fine.

Digital Identity applet will not run as ordinary user
CMBrown
I have tried to replicate this on a newer version of the WinFX Framework and the applet works fine.
I would assume at this point that it was a bug in those earlier versions of the WinFX Framework, and it will work fine with the May CTP when it ships.
Garrett