Fields applied to the User area are not translatable? I have a site which allows people to register as a member from the front end. I've got a bunch of fields attached to the User so that each person can build their own extended profile page; the site is bilingual. I've successfully got fields translatable when they're attached to a Section (the fields are marked as translatable), but when the same fields are attached to User there appears to be no way to input content in a different language; the familiar language switch in the back-end is not there... what am I missing?

E.g., here is the biography field, marked as translatable:



Here is the result when the field is used in a Section (note the interface has a language switch on the right, which can be toggled and the contents of the biography field changes):



But here is the same field when used in a User, note the lack of a way to change the language:



Bonus Question:
Assuming these fields are translatable; how would I get the front-end user form to list the fields in both English and Welsh so the user could fill in both on one page (i.e., without them needing to switch the site itself into another language)?
You're not missing anything; user content is currently not translatable. (It's up to each type of element whether it wants to support translatable content, and we felt that 99% of the time it would not be desirable for users to have translatable profiles.