As I understand it, the IBC was the conglomeration of the Uniform Building Code, the Southern Building Code and some third code whose name escapes me, all of which were US building codes. It is only applicable where a jurisdiction adopts it, and, unlike the way the map shows, that is not all of the US.
If used internationally, the most likely use would be in places that don't currently have any building code- I don't think anyone expects, say, France, to drop their current building codes and take up with IBC.
icenine has it right. There used to be 3 major building codes in the USA. BOCA (Building Officals & Code Aministrators) was used primariliy in the northeast, UBC (Uniform Building Code) in the west and SBC (Standard Building Code). They finally got together and produced the IBC, with a first release in 2000. IBC is updated every 3 years, the 2006 version just came out recently.
Note that in addition to not being used in most of the non-US world, the IBC also doesn't include design information outside the US. So if you want to use it elsewhere, you're on your own to come up with wind speeds, etc.
I note that ICC does in fact have an international group, and actually has an office in Argentina:
I also ran across this link, where ICC codes are being used in development of Mexican building codes, although it doesn't sound like a direct adoption of IBC is going to take place anytime soon:
Generally, where construction companies and engineers work across borders, there's a good incentive to use the same building code on both sides, and I assume that's the motivation with the Eurocodes. Where that doesn't happen, it doesn't much matter, though.
