@eureka: Does it?
A file with the `i' attribute cannot be modified: it cannot be deleted or renamed, no link can be created to this file and no data can be written to the file. Only the superuser or a process possessing the CAP_LINUX_IMMUTABLE capability can set or clear this attribute.
diags runs as root, too, no?
(I've never used xattr at all, so I'm trusting my interpretation of the manpage here, didn't check at all what actually happens on the Kindle
That said, in my/USBNet case, the point is moot: I don't store anything in /usr/local (but it's nonetheless good to know if this actually works
EDIT: I can't read >_<". '[...] can set or clear this attribute
' (meaning the perm/cap refers to manipulating the xattr, not the file itself, so yup, should work). /me needs more coffee.