EDIT: Another way of asking this same question, I guess, is: is there an out of the box web service to which I can pass an email address as a parameter, and get other properties for that user back as a result?
So, I have used this neat trick to pull in the current user information: InfoPath - Get the current user without writing code
Now, I have a different scenario that I need to implement. I have a form that will be pre-populated with the user's email address, and I want to access other properties of their profile using the email address as the key.
The GetUserProfileByName web service seems to be the right one to use, but I want to be able to pass it a value from the form and return the profile information I need (in this case, the user's manager).