The Brent Weeks ebook was presumably US-only. However, mobipocket.com usually lists country restrictions on each ebook's web page and its three Brent Weeks ebooks have no such restrictions. See for example
Orphan's Destiny by Robert Buettner, which is another Orbit ebook that is restricted.
Has anyone come across any non-US-only ebooks on BoB? In other words, is there a downside to registering as a US resident?