Hello,
I just uploaded this patch: http://dev.rubyonrails.org/ticket/11112
The point is URI restricts username and password and, for example, you cannot use emails as usernames.
I have patched ActiveResource to allow the following syntax: class Person < ActiveResource::Base self.site = “http://api.people.com:3000/”
self.user = “ryan”
self.password = “password” end
Patch includes tests and updated doc.
Feedback is welcome 
Cheers