Its spelled Niobium..its a proprietary alloy (containing niobium of course) thats supposed to be very light and strong. All I know is my Niobium 30s cost about the same as deepvs and are as deep as deepVs but they are a lot lighter.

I think they come from Asia (probably Tiawan) and there are several people who sell them or build with them. However, the main person who seems to use them is Mike Garcia, a builder who has a very good reputation on the roadie forum. Thats where I got mine. You'll find info about the rim on his website or you can call up Mike Garcia and ask him.

http://oddsandendos.safeshopper.com/index.htm?192

I guarantee you he'll talk you ear off telling you more than you need or want to know, and even give you some really solid advice about how many spokes you need etc.