I'm experimenting with DotNetOpenAuth and I realized (at least as far as Google goes) if I registered with www.domain.com my claimed identifier is different than domain.com.
I had the impression setting the realm would fix this issue but it didnt.
For now I believe I have solved the problem using url rewriting.
Is there a better way?
Setting the realm so that it always includes the www. prefix or never does will in fact fix this problem. However you must also make sure that the ReturnUrl (i.e. return_to) has the same host name as the realm so you may have to apply the same modifier to that as you do to the realm.