If you have control of a domain (in any TLD) -- in other words, you can specify the DNS servers for it (which excludes cases like .io where they don't give you such control, keeping it at the registry) -- you can create as many subdomains as you want and point them wherever you want; the registry and registrar have no control of that.
In some cases, the registration agreements might attempt to restrict what you can do with subdomains; for instance, the .museum registration agreement says you can't use subdomains for any non-museum-related purpose, and the .tv agreement says you can't provide subdomain registrations to other parties besides yourself. However, any such restrictions would have to be enforced by them threatening to revoke your domain for violating them; they have no way to automatically prevent such use. It's anyone's guess whether such restrictions would prove to be legally enforceable if a registry tried it.
.name is no different from any other domain in this regard; if you own joe.blow.name, you can create subdomains like iam.joe.blow.name, youare.joe.blow.name, etc. The only difference is that the level you control is third-level rather than second-level; you can't create names like jane.blow.name because you don't control blow.name, even if you use their email forwarding to get
[email protected].
The same is true of co.uk, com.au, art.museum, or any other domain where you can only register at the third level beneath a registry-controlled second level.
Of course, the server hosting your domain needs to be able to handle the subdomains; if it's a server you own yourself, you can configure them at no cost (get the O'Reilly book "DNS and BIND" to find out how), but if it's at a hosting provider you're subject to their policies, which might impose costs or limits. My own host, Dreamhost, allows 5 fully hosted subdomains per main domain at no extra charge, and an unlimited number of mirrored or redirected ones.
