Currently DotNetNuke supports the use of personal cards when using CardSpace and the Identity Metasystem. This is a step forward in terms of dealing with up and coming digital identity management.
In its current form CardSpace cannot support holding a user's custom profile attributes as a personal card is locked down to just a few pieces of information.
This is going to change. I've just started implementing a Secure Token Server for DotNetNuke based on the newly announced sharpSTS project.
Soon, you'll be able to issue your own managed cards through DotNetNuke, which include all the users personal information. I'm also going to write a new provider for DotNetNuke that will allow webmasters to declare what information they should save in their databases.
As a webmaster you'll be able to offer your customers all the personalisation they expect, while offloading privacy and security concerns.
If you are interested in helping out then please let me know.