What you do is a bit more complicated, but has the benefit of making your data "private" within a closure. You are using a function as an object, and assigning other functions as fields within its "prototype". I think these inner functions can call each other w/out a prefix, as methods of the same object.
My version is the "static method" version that requires the namespace and a dot before any function calls. I'm OK with that, unless I need a bunch of instances of something.
P.S. - the semicolons don't really do anything (other than make Doug C feel good), as JS is a line oriented language, and will complete statements when they "look done", semis or not. Think of semicolons in JS like colons in BASIC: they let you put a second statement on the same line.